Method of broadcast gateway signaling for channel bonding, and apparatus for the same

ABSTRACT

Disclosed herein are a method and apparatus of broadcast gateway signaling for channel bonding. The apparatus for broadcast gateway signaling includes an input formatting unit configured to generate baseband packets corresponding to channel bonding; and a stream partitioner configured to allocate the baseband packets to two or more RF channels of the channel bonding for generating an outer tunnel data stream, the outer tunnel data stream generated in different ways according to a plurality of operation modes for the channel bonding.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a Continuation Application of U.S. Pat. ApplicationNo. 17/476,578, filed on Sep. 16, 2021, which is a ContinuationApplication of U.S. Pat. Application No. 16/659,738, filed on Oct. 22,2019, which claims the benefit of Korean Patent Application No.10-2018-0126332, filed Oct. 22, 2018, and No. 10-2019-0127736, filedOct. 15, 2019, which are hereby incorporated by reference in theirentireties into this application.

BACKGROUND OF THE INVENTION 1. Technical Field

The present invention relates generally to technology for transmittingbroadcast signals, and more particularly to a broadcast signaltransmitter for transmitting broadcast signals and a broadcast gatewayapparatus for providing broadcast data to the broadcast signaltransmitter.

2. Description of the Related Art

In terrestrial broadcasting, a Single-Frequency Network (SFN) hasemerged as an alternative to conventional Multiple-Frequency Network(MFN) modes. An SFN is configured such that multiple transmitterssimultaneously transmit signals on the same RF channel.

For a broadcast service, multiple transmitters are provided withbroadcast data from a broadcast gateway apparatus, generate broadcastsignals for a broadcast service using the broadcast data, and transmitthe broadcast signals to receivers.

Various broadcast signal transmission/reception techniques have beendeveloped in order to transmit and receive broadcast signals between atransmitter and a receiver, but there has been little focus on thedevelopment of signal transmission/reception technology on atransmission-system side.

Particularly, new data transmission technology, which is capable ofefficiently transmitting broadcast data from a broadcast gatewayapparatus to a transmitter while guaranteeing reliability regardless ofthe state or type of network that is used, and broadcast gatewaysignaling technology therefor are required.

SUMMARY OF THE INVENTION

An object of the present invention is to generate each broadcasttransmission signal corresponding to each RF channel efficiently whenthe channel bonding is performed using two or more RF channels.

Furthermore, an object of the present invention is to efficientlyprovide a channel bonding service by appropriately sharing roles of abroadcast gateway and a transmitter.

Furthermore, an objective of the present invention is to optimize thethroughput of a broadcast gateway apparatus even when SNR averagingchannel bonding is applied.

Furthermore, an object of the present invention is to optimize abroadcast-gateway-signaling field for the channel bonding service.

In order to accomplish the above objects, the present invention providesa broadcast gateway signaling apparatus, comprising: an input formattingunit configured to generate baseband packets corresponding to channelbonding; and a stream partitioner configured to allocate the basebandpackets to two or more RF channels of the channel bonding for generatingan outer tunnel data stream. In this case, the outer tunnel data streamis generated in different ways according to a plurality of operationmodes for the channel bonding.

In this case, the plurality of operation modes may include a first modein which one outer tunnel data stream is generated for each of the twoor more RF channels; and a second mode in which one outer tunnel datastream for the two or more RF channels is generated.

In this case, the one outer tunnel data stream for the first mode mayinclude one inner tunneled packet stream group for one among the two ormore RF channels, and the one outer tunnel data stream of the secondmode may include two or more inner tunneled packet stream groups whichare for the two or more RF channels, respectively.

In this case, the outer tunnel data stream may be transmitted to atransmitter through a Studio-to-Transmitter Link (STL), and maycorrespond to an outer layer of a tunneling system and the innertunneled packet stream group may correspond to an inner layer of thetunneling system.

In this case, the two or more inner tunneled packet stream groups of thesecond mode may use different port groups.

In this case, the second mode may use two outer tunnel data streams fortwo non-colocated transmitters corresponding to SNR averaging channelbonding. In this case, each of the two outer tunnel data streams mayinclude two inner tunneled packet stream groups which use different portgroups.

In this case, the two or more RF channels may be two RF channels, and afirst port group corresponding to ports 30000 - 30066 may be used forthe inner tunneled packet stream group corresponding to a first channelamong the two RF channels and a second port group corresponding to ports30100 - 30166 may be used for the inner tunneled packet stream groupcorresponding to a second channel among the two RF channels.

In this case, the outer tunnel data stream may include a RTP headerwhich includes a channel number field (number_of_channels) thatindicates the number of channels corresponding to the outer tunnel datastream.

In this case, the channel number field may be 2-bit field, and may beset to ‘0’ for the first mode and may be set to ‘1’ for the second mode.

Furthermore, an embodiment of the present invention provides anapparatus of transmitting a broadcast signal, comprising: a STL receiverconfigured to receive an outer tunnel data stream transmitted through aStudio-to-Transmitter Link (STL), the outer tunnel data streamcorresponding to channel bonding; a BICM unit configured to performerror correction encoding, interleaving and modulation corresponding toone among two or more RF channels corresponding to the channel bonding;and a waveform generator configured to generate a RF transmission signalcorresponding to the one among two or more RF channels.

In this case, the outer tunnel data stream may be generated in differentways according to a plurality of operation modes for the channelbonding.

In this case, the plurality of operation modes may include a first modein which one outer tunnel data stream is generated for each of the twoor more RF channels; and a second mode in which one outer tunnel datastream for the two or more RF channels is generated.

In this case, the one outer tunnel data stream of the first mode mayinclude one inner tunneled packet stream group for one among the two ormore RF channels, and the one outer tunnel data stream of the secondmode may include two or more inner tunneled packet stream groups whichare for the two or more RF channels, respectively.

In this case, the two or more inner tunneled packet stream groups of thesecond mode may use different port groups.

In this case, the outer tunnel data stream may include a RTP headerwhich include a channel number field (number_of_channels) that indicatesthe number of channels corresponding to the outer tunnel data stream.

Furthermore, an embodiment of the present invention provides abroadcast-gateway-signaling method, comprising: generating basebandpackets corresponding to channel bonding; and allocating the basebandpackets to two or more RF channels of the channel bonding for generatingan outer tunnel data stream. In this case, the outer tunnel data streamis generated in different ways according to a plurality of operationmodes for the channel bonding.

In this case, the plurality of operation modes may include a first modein which one outer tunnel data stream is generated for each of the twoor more RF channels; and a second mode in which one outer tunnel datastream for the two or more RF channels is generated.

In this case, the one outer tunnel data stream for the first mode mayinclude one inner tunneled packet stream group for one among the two ormore RF channels, and the one outer tunnel data stream of the secondmode may include two or more inner tunneled packet stream groups whichare for the two or more RF channels, respectively.

In this case, the two or more inner tunneled packet stream groups of thesecond mode may use different port groups.

In this case, the outer tunnel data steam may include a RTP header whichinclude a channel number field (number_of_channels) that indicates thenumber of channels corresponding to the outer tunnel data stream.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects, features and advantages of the presentinvention will be more clearly understood from the following detaileddescription taken in conjunction with the accompanying drawings, inwhich:

FIG. 1 is a block diagram showing a broadcast signaltransmission/reception system according to an embodiment of the presentinvention;

FIG. 2 is an operation flowchart showing a broadcast signaltransmission/reception method according to an embodiment of the presentinvention;

FIG. 3 is a block diagram showing an example of the apparatus forgenerating broadcast signal frame in FIG. 1 ;

FIG. 4 is a diagram showing an example of the structure of a broadcastsignal frame;

FIG. 5 is a diagram showing an example of the receiving process of thebroadcast signal frame shown in FIG. 4 ;

FIG. 6 is a diagram showing another example of the receiving process ofthe broadcast signal frame shown in FIG. 4 ;

FIG. 7 is a block diagram showing another example of the apparatus forgenerating broadcast signal frame shown in FIG. 1 ;

FIG. 8 is a block diagram showing an example of the signal demultiplexershown in FIG. 1 ;

FIG. 9 is a block diagram showing an example of the core layer BICMdecoder and the enhanced layer symbol extractor shown in FIG. 8 ;

FIG. 10 is a block diagram showing another example of the core layerBICM decoder and the enhanced layer symbol extractor shown in FIG. 8 ;

FIG. 11 is a block diagram showing still another example of the corelayer BICM decoder and the enhanced layer symbol extractor shown in FIG.8 ;

FIG. 12 is a block diagram showing another example of the signaldemultiplexer shown in FIG. 1 ;

FIG. 13 is a diagram showing an increase in power attributable to thecombination of a core layer signal and an enhanced layer signal;

FIG. 14 is an operation flowchart showing a method of generatingbroadcast signal frame according to an embodiment of the presentinvention;

FIG. 15 is a diagram showing a structure of a super-frame which includesbroadcast signal frames according to an embodiment of the presentinvention;

FIG. 16 is a diagram showing an example of an LDM frame includingmultiple-physical layer pipes and using LDM of two layers;

FIG. 17 is a diagram showing another example of an LDM frame includingmultiple-physical layer pipes and using LDM of two layers;

FIG. 18 is a diagram showing an application example of an LDM frameusing multiple-physical layer pipes and LDM of two layers;

FIG. 19 is a diagram showing another application example of an LDM frameusing multiple-physical layer pipes and LDM of two layers;

FIG. 20 is a block diagram showing a channel bonding transmitter;

FIG. 21 is a block diagram showing a channel bonding receiver;

FIG. 22 is a block diagram showing a broadcast signal transmitter withan input formatting block for BB header insertion;

FIG. 23 is a block diagram showing a broadcast signal receiver with ablock for BB header removal;

FIG. 24 is a diagram for explaining an operation of the cell exchanger;

FIG. 25 is a diagram for mathematically expressing the output of thecell exchanger;

FIG. 26 is a block diagram showing an apparatus for transmittingbroadcast signal using SNR averaging CB and same band allocation;

FIG. 27 is a block diagram showing an apparatus for receiving broadcastsignal using SNR averaging CB and same band allocation;

FIG. 28 is a block diagram showing an apparatus for transmittingbroadcast signal using plain CB and different bands allocation;

FIG. 29 is a block diagram showing a mobile receiver using plain CB anddifferent bands allocation;

FIG. 30 is a block diagram showing a fixed receiver using plain CB anddifferent bands allocation;

FIG. 31 is a block diagram showing an apparatus for transmittingbroadcast signal according to an embodiment of the present invention;

FIG. 32 is a block diagram showing a mobile broadcast signal receiversaccording to an embodiment of the present invention;

FIG. 33 is a block diagram showing a fixed broadcast signal receiveraccording to an embodiment of the present invention;

FIG. 34 is a block diagram showing an apparatus for transmittingbroadcast signal according to another embodiment of the presentinvention;

FIG. 35 is a block diagram showing a mobile broadcast signal receiveraccording to another embodiment of the present invention;

FIG. 36 is a block diagram showing a fixed broadcast signal receiveraccording to another embodiment of the present invention;

FIG. 37 is an operation flowchart showing a method of transmittingbroadcast signal according to an embodiment of the present invention;

FIG. 38 is a block diagram showing one exemplarily embodiment of anapparatus for transmitting broadcast signal to which channel bonding isapplied;

FIG. 39 is a block diagram showing a case in which the input formattingunit of FIG. 38 generates baseband packets for two PLPs;

FIG. 40 is a block diagram showing a case in which the input formattingunit of FIG. 38 channel-bonds two RF channels;

FIG. 41 is an operation flowchart showing a method of transmittingbroadcast signal using channel bonding according to an embodiment of thepresent invention;

FIG. 42 is a block diagram showing a broadcast signal transmissionsystem according to an embodiment of the present invention;

FIG. 43 is a block diagram showing one exemplarily embodiment of abroadcast signal transmission system when plain channel bonding forcolocated transmitters is applied;

FIG. 44 is a block diagram showing one exemplarily embodiment of abroadcast signal transmission system when plain channel bonding fornon-colocated transmitters is applied;

FIG. 45 is a block diagram showing one exemplarily embodiment of abroadcast signal transmission system when SNR averaging channel bondingfor colocated transmitters is applied;

FIG. 46 is a block diagram showing one exemplarily embodiment of abroadcast signal transmission system when SNR averaging channel bondingfor non-colocated transmitters is applied;

FIG. 47 is an operation flowchart showing an example of abroadcast-gateway-signaling method according to an embodiment of thepresent invention;

FIG. 48 is an operation flowchart showing an example of a broadcastsignal transmission method according to an embodiment of the presentinvention; and

FIG. 49 is a block diagram showing a computer system according to anembodiment of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention will be described in detail below with referenceto the accompanying drawings. Repeated descriptions and descriptions ofknown functions and configurations which have been deemed to make thegist of the present invention unnecessarily obscure will be omittedbelow. The embodiments of the present invention are intended to fullydescribe the present invention to a person having ordinary knowledge inthe art to which the present invention pertains. Accordingly, theshapes, sizes, etc. of components in the drawings may be exaggerated inorder to make the description clearer.

Hereinafter, a preferred embodiment according to the present inventionwill be described in detail with reference to the accompanying drawings.

FIG. 1 is a block diagram showing a broadcast signaltransmission/reception system according to an embodiment of the presentinvention.

Referring to FIG. 1 , a broadcast signal transmission/reception systemaccording to the embodiment of the present invention includes abroadcast signal transmission apparatus 110, a wireless channel 120, anda broadcast signal reception apparatus 130.

The broadcast signal transmission apparatus 110 includes an apparatusfor generating broadcast signal frame 111 which generate the broadcastsignal frame by multiplexing core layer data and enhanced layer data,and an OFDM transmitter 113.

The apparatus 111 combines a core layer signal corresponding to corelayer data and an enhanced layer signal corresponding to enhanced layerdata at different power levels, and generates a multiplexed signal byperforming interleaving that is applied to both the core layer signaland the enhanced layer signal. In this case, the apparatus 111 maygenerate a broadcast signal frame including a bootstrap and a preambleusing a time-interleaved signal. In this case, the broadcast signalframe may be an ATSC 3.0 frame.

The OFDM transmitter 113 transmits the multiplexed signal using an OFDMcommunication method via an antenna 117, thereby allowing thetransmitted OFDM signal to be received via the antenna 137 of thebroadcast signal reception apparatus 130 over the wireless channel 120.

The broadcast signal reception apparatus 130 includes an OFDM receiver133 and a signal demultiplexer 131. When the signal transmitted over thewireless channel 120 is received via the antenna 137, the OFDM receiver133 receives an OFDM signal via synchronization, channel estimation andequalization.

In this case, the OFDM receiver 133 may detect and demodulate thebootstrap from the OFDM signal, demodulate the preamble usinginformation included in the bootstrap, and demodulate the super-imposedpayload using information included in the preamble.

The signal demultiplexer 131 restores the core layer data from thesignal (super-imposed payload) received via the OFDM receiver 133 first,and then restores the enhanced layer data via cancellation correspondingto the restored core layer data. In this case, the signal demultiplexer131 may generate a broadcast signal frame first, may restore thebootstrap, may restore the preamble using the information included inthe bootstrap, and may use the signaling information included in thepreamble for the restoration of a data signal. In this case, thesignaling information may be L1 signaling information and may includeinjection level information, normalizing factor information, etc.

In this case, the preamble may include a PLP identification informationfor identifying Physical Layer Pipes (PLPs); and a layer identificationinformation for identifying layers corresponding to division of layers.

In this case, the PLP identification information and the layeridentification information may be included in the preamble as fieldsdifferent from each other.

In this case, the time interleaver information may be included in thepreamble for each of the Physical Layer Pipes (PLPs) without checking acondition of a conditional statement corresponding to the layeridentification information.

In this case, the preamble may selectively include an injection levelinformation corresponding to the injection level controller for each ofthe Physical Layer Pipes (PLPs) based on a result of comparing the layeridentification information with a predetermined value.

In this case, the preamble may include type information, start positioninformation and size information of the Physical Layer Pipes

In this case, the type information may be for identifying one among afirst type corresponding to a non-dispersed physical layer pipe and asecond type corresponding to a dispersed physical layer pipe.

In this case, the non-dispersed physical layer pipe may be assigned forcontiguous data cell indices, and the dispersed physical layer pipe mayinclude two or more subslices.

In this case, the type information may be selectively signaled accordingto a result of comparing the layer identification information with apredetermined value for each of the Physical Layer Pipes (PLPs).

In this case, the type information may be signaled only for the corelayer.

In this case, the start position information may be identical to anindex corresponding to the first data cell of the physical layer pipe.

In this case, the start position information may indicate the startposition of the physical layer pipe using cell addressing scheme.

In this case, the start position information may be included in thepreamble for each of the Physical Layer Pipes (PLPs) without checking acondition of a conditional statement corresponding to the layeridentification information.

In this case, the size information may be generated based on the numberof data cells assigned to the physical layer pipe.

In this case, the size information may be included in the preamble foreach of the Physical Layer Pipes (PLPs) without checking a condition ofa conditional statement corresponding to the layer identificationinformation.

As will be described in detail later, the apparatus 111 shown in FIG. 1may include a combiner configured to generate a multiplexed signal bycombining a core layer signal and an enhanced layer signal at differentpower levels; a power normalizer configured to reduce the power of themultiplexed signal to a power level corresponding to the core layersignal; a time interleaver configured to generate a time-interleavedsignal by performing interleaving that is applied to both the core layersignal and the enhanced layer signal; and a frame builder configured togenerate a broadcast signal frame including a preamble for signaling,size information of Physical Layer Pipes (PLPs) and time interleaverinformation shared by the core layer signal and the enhanced layersignal, using the time-interleaved signal. In this case, the broadcastsignal transmission apparatus 110 shown in FIG. 1 may be viewed asincluding: a combiner configured to generate a multiplexed signal bycombining a core layer signal and an enhanced layer signal at differentpower levels; a power normalizer configured to reduce the power of themultiplexed signal to a power level corresponding to the core layersignal; a time interleaver configured to generate a time-interleavedsignal by performing interleaving that is applied to both the core layersignal and the enhanced layer signal; a frame builder configured togenerate a broadcast signal frame including a preamble for signalingsize information of Physical Layer Pipes (PLPs) and time interleaverinformation shared by the core layer signal and the enhanced layersignal, using the time-interleaved signal; and an OFDM transmitterconfigured to transmit the broadcast signal frame using OFDMcommunication scheme through an antenna.

As will be described in detail later, the signal demultiplexer shown inFIG. 1 may include a time deinterleaver configured to generate atime-deinterleaved signal by applying time deinterleaving to a receivedsignal corresponding to a broadcast signal frame; a de-normalizerconfigured to increase the power of the received signal or thetime-deinterleaved signal by a level corresponding to a reduction inpower by the power normalizer of the transmitter; a core layer BICMdecoder configured to restore core layer data from the signalpower-adjusted by the de-normalizer; an enhanced layer symbol extractorconfigured to extract an enhanced layer signal by performingcancellation corresponding to the core layer data on the signalpower-adjusted by the de-normalizer using the output signal of the corelayer FEC decoder of the core layer BICM decoder; a de-injection levelcontroller configured to increase the power of the enhanced layer signalby a level corresponding to a reduction in power by the injection levelcontroller of the transmitter; and an enhanced layer BICM decoderconfigured to restore enhanced layer data using the output signal of thede-injection level controller. In this case, the broadcast signalreception apparatus 130 shown in FIG. 1 may be viewed as including: anOFDM receiver configured to generate a received signal by performing anyone or more of synchronization, channel estimation and equalization on atransmitted signal corresponding to a broadcast signal frame; a timedeinterleaver configured to generate a time-deinterleaved signal byapplying time deinterleaving to the received signal; a de-normalizerconfigured to increase the power of the received signal or thetime-deinterleaved signal by a level corresponding to a reduction inpower by the power normalizer of the transmitter; a core layer BICMdecoder configured to restore core layer data from the signalpower-adjusted by the de-normalizer; an enhanced layer symbol extractorconfigured to extract an enhanced layer signal by performingcancellation corresponding to the core layer data on the signalpower-adjusted by the de-normalizer using the output signal of the corelayer FEC decoder of the core layer BICM decoder; a de-injection levelcontroller configured to increase the power of the enhanced layer signalby a level corresponding to a reduction in power by the injection levelcontroller of the transmitter; and an enhanced layer BICM decoderconfigured to restore enhanced layer data using the output signal of thede-injection level controller.

Although not explicitly shown in FIG. 1 , a broadcast signaltransmission/reception system according to an embodiment of the presentinvention may multiplex/demultiplex one or more pieces of extensionlayer data in addition to the core layer data and the enhanced layerdata. In this case, the extension layer data may be multiplexed at apower level lower than that of the core layer data and the enhancedlayer data. Furthermore, when two or more extension layers are included,the injection power level of a second extension layer may be lower thanthe injection power level of a first extension layer, and the injectionpower level of a third extension layer may be lower than the injectionpower level of the second extension layer.

FIG. 2 is an operation flowchart showing a broadcast signaltransmission/reception method according to an embodiment of the presentinvention.

Referring to FIG. 2 , in the broadcast signal transmission/receptionmethod according to the embodiment of the present invention, a corelayer signal and an enhanced layer signal are combined at differentpower levels and then multiplexed to generate a broadcast signal frameincluding a preamble for signaling size information of Physical LayerPipes (PLPs) and time interleaver information shared by the core layersignal and the enhanced layer signal at step S210.

In this case, the broadcast signal frame generated at step S210 mayinclude the bootstrap, the preamble and a super-imposed payload. In thiscase, at least of the bootstrap and the preamble may include L1signaling information. In this case, the L1 signaling information mayinclude injection level information and normalizing factor information.

In this case, the preamble may include a PLP identification informationfor identifying Physical Layer Pipes (PLPs); and a layer identificationinformation for identifying layers corresponding to division of layers.

In this case, the PLP identification information and the layeridentification information may be included in the preamble as fieldsdifferent from each other.

In this case, the time interleaver information may be included in thepreamble for each of the Physical Layer Pipes (PLPs) without checking acondition of a conditional statement corresponding to the layeridentification information.

In this case, the preamble may selectively include an injection levelinformation corresponding to the injection level controller for each ofthe Physical Layer Pipes (PLPs) based on a result of comparing the layeridentification information with a predetermined value.

In this case, the preamble may include type information, start positioninformation and size information of the Physical Layer Pipes

In this case, the type information may be for identifying one among afirst type corresponding to a non-dispersed physical layer pipe and asecond type corresponding to a dispersed physical layer pipe.

In this case, the non-dispersed physical layer pipe may be assigned forcontiguous data cell indices, and the dispersed physical layer pipe mayinclude two or more subslices.

In this case, the type information may be selectively signaled accordingto a result of comparing the layer identification information with apredetermined value for each of the Physical Layer Pipes (PLPs).

In this case, the type information may be signaled only for the corelayer.

In this case, the start position information may be identical to anindex corresponding to the first data cell of the physical layer pipe.

In this case, the start position information may indicate the startposition of the physical layer pipe using cell addressing scheme.

In this case, the start position information may be included in thepreamble for each of the Physical Layer Pipes (PLPs) without checking acondition of a conditional statement corresponding to the layeridentification information.

In this case, the size information may be generated based on the numberof data cells assigned to the physical layer pipe.

In this case, the size information may be included in the preamble foreach of the Physical Layer Pipes (PLPs) without checking a condition ofa conditional statement corresponding to the layer identificationinformation.

Furthermore, in the broadcast signal transmission/reception methodaccording to the embodiment of the present invention, the broadcastsignal frame is OFDM transmitted at step S220.

Furthermore, in the broadcast signal transmission/reception methodaccording to the embodiment of the present invention, the transmittedsignal is OFDM received at step S230.

In this case, at step S230, synchronization, channel estimation andequalization may be performed.

In this case, the bootstrap may be restored, the preamble may berestored using a signal included in the restored bootstrap, and the datasignal may be restored using the signaling information included in thepreamble at step S230.

Furthermore, in the broadcast signal transmission/reception methodaccording to the embodiment of the present invention, core layer data isrestored from the received signal at step S240.

Furthermore, in the broadcast signal transmission/reception methodaccording to the embodiment of the present invention, enhanced layerdata is restored via the cancellation of the core layer signal at stepS250.

In particular, steps S240 and S250 shown in FIG. 2 may correspond todemultiplexing operations corresponding to step S210.

As will be described in detail later, step S210 shown in FIG. 2 mayinclude generating a multiplexed signal by combining a core layer signaland an enhanced layer signal at different power levels; reducing thepower of the multiplexed signal to a power level corresponding to thecore layer signal; generating a time-interleaved signal by performinginterleaving that is applied to both the core layer signal and theenhanced layer signal; and generating a broadcast signal frame includinga preamble for signaling size information of Physical Layer Pipes (PLPs)and time interleaver information shared by the core layer signal and theenhanced layer signal, using the time-interleaved signal.

In this case, the broadcast signal transmission method of steps S210 andS220 may be viewed as including generating a multiplexed signal bycombining a core layer signal and an enhanced layer signal at differentpower levels; reducing the power of the multiplexed signal to a powerlevel corresponding to the core layer signal; generating atime-interleaved signal by performing interleaving that is applied toboth the core layer signal and the enhanced layer signal; generating abroadcast signal frame including a preamble for signaling sizeinformation of Physical Layer Pipes (PLPs) and time interleaverinformation shared by the core layer signal and the enhanced layersignal, using the time-interleaved signal; and transmitting thebroadcast signal frame using an OFDM communication scheme through anantenna.

As will be described in detail later, steps S240 and S250 shown in FIG.2 may include generating a time-deinterleaved signal by applying timedeinterleaving to a received signal corresponding to a broadcast signalframe; increasing the power of the received signal or thetime-deinterleaved signal by a level corresponding to a reduction inpower by the power normalizer of the transmitter; restoring core layerdata from the power-adjusted signal; extracting an enhanced layer signalby performing cancellation corresponding to the core layer data on thepower-adjusted signal; increasing the power of the enhanced layer signalby a level corresponding to a reduction in power by the injection levelcontroller of the transmitter; and restoring enhanced layer data usingthe power-adjusted enhanced signal. In this case, a broadcast signalreception method according to an embodiment of the present invention maybe viewed as including: generating a received signal by performing anyone or more of synchronization, channel estimation and equalization on atransmitted signal corresponding to a broadcast signal frame; generatinga time-deinterleaved signal by applying time deinterleaving to thereceived signal; increasing the power of the received signal or thetime-deinterleaved signal by a level corresponding to a reduction inpower by the power normalizer of the transmitter; restoring core layerdata from the power-adjusted signal; extracting an enhanced layer signalby performing cancellation corresponding to the core layer data on thepower-adjusted signal; increasing the power of the enhanced layer signalby a level corresponding to a reduction in power by the injection levelcontroller of the transmitter; and restoring enhanced layer data usingthe power-adjusted enhanced layer signal.

FIG. 3 is a block diagram showing an example of the apparatus forgenerating broadcast signal frame in FIG. 1 .

Referring to FIG. 3 , the apparatus for generating broadcast signalframe according to an embodiment of the present invention may include acore layer BICM unit 310, an enhanced layer BICM unit 320, an injectionlevel controller 330, a combiner 340, a power normalizer 345, and a timeinterleaver 350, a signaling generation unit 360, and a frame builder370.

Generally, a BICM device includes an error correction encoder, a bitinterleaver, and a symbol mapper. Each of the core layer BICM unit 310and the enhanced layer BICM unit 320 shown in FIG. 3 may include anerror correction encoder, a bit interleaver, and a symbol mapper. Inparticular, each of the error correction encoders (the core layer FECencoder, and the enhanced layer FEC encoder) shown in FIG. 3 may beformed by connecting a BCH encoder and an LDPC encoder in series. Inthis case, the input of the error correction encoder is input to the BCHencoder, the output of the BCH encoder is input to the LDPC encoder, andthe output of the LDPC encoder may be the output of the error correctionencoder.

As shown in FIG. 3 , core layer data and enhanced layer data passthrough respective different BICM units, and are then combined by thecombiner 340. That is, the term “Layered Division Multiplexing (LDM)”used herein may refer to combining the pieces of data of a plurality oflayers into a single piece of data using differences in power and thentransmitting the combined data.

That is, the core layer data passes through the core layer BICM unit310, the enhanced layer data passes through the enhanced layer BICM unit320 and then the injection level controller 330, and the core layer dataand the enhanced layer data are combined by the combiner 340. In thiscase, the enhanced layer BICM unit 320 may perform BICM encodingdifferent from that of the core layer BICM unit 310. That is, theenhanced layer BICM unit 320 may perform higher bit rate errorcorrection encoding or symbol mapping than the core layer BICM unit 310.Furthermore, the enhanced layer BICM unit 320 may perform less robusterror correction encoding or symbol mapping than the core layer BICMunit 310.

For example, the core layer error correction encoder may exhibit a lowerbit rate than the enhanced layer error correction encoder. In this case,the enhanced layer symbol mapper may be less robust than the core layersymbol mapper.

The combiner 340 may be viewed as functioning to combine the core layersignal and the enhanced layer signal at different power levels. In anembodiment, power level adjustment may be performed on the core layersignal rather than the enhanced layer signal. In this case, the power ofthe core layer signal may be adjusted to be higher than the power of theenhanced layer signal.

The core layer data may use forward error correction (FEC) code having alow code rate in order to perform robust reception, while the enhancedlayer data may use FEC code having a high code rate in order to achievea high data transmission rate.

That is, the core layer data may have a broader coverage than theenhanced layer data in the same reception environment.

The enhanced layer data having passed through the enhanced layer BICMunit 320 is adjusted in gain (or power) by the injection levelcontroller 330, and is combined with the core layer data by the combiner340.

That is, the injection level controller 330 generates a power-reducedenhanced layer signal by reducing the power of the enhanced layersignal. In this case, the magnitude of the signal adjusted by theinjection level controller 330 may be determined based on an injectionlevel. In this case, an injection level in the case where signal B isinserted into signal A may be defined by Equation 1 below:

$\begin{matrix}{\text{Injection level}\left( \text{dB} \right) = - 10\text{log}_{10}\left( \frac{\text{Signal power of B}}{\text{Signal power of A}} \right)} & \text{­­­(1)}\end{matrix}$

For example, assuming that the injection level is 3 dB when the enhancedlayer signal is inserted into the core layer signal, Equation 1 meansthat the enhanced layer signal has power corresponding to half of thepower of the core layer signal.

In this case, the injection level controller 330 may adjust the powerlevel of the enhanced layer signal from 0 dB to 25.0 dB in steps of 0.5dB or 1 dB.

In general, transmission power that is assigned to the core layer ishigher than transmission power that is assigned to the enhanced layer,which enables the receiver to decode core layer data first.

In this case, the combiner 340 may be viewed as generating a multiplexedsignal by combining the core layer signal with the power-reducedenhanced layer signal.

The signal obtained by the combination of the combiner 340 is providedto the power normalizer 345 so that the power of the signal can bereduced by a power level corresponding to an increase in power caused bythe combination of the core layer signal and the enhanced layer signal,and then power adjustment is performed. That is, the power normalizer345 reduces the power of the signal, obtained by the multiplexing of thecombiner 340, to a power level corresponding to the core layer signal.Since the level of the combined signal is higher than the level of onelayer signal, the power normalizing of the power normalizer 345 isrequired in order to prevent amplitude clipping, etc. in the remainingportion of a broadcast signal transmission/reception system.

In this case, the power normalizer 345 may adjust the magnitude of thecombined signal to an appropriate value by multiplying the magnitude ofthe combined signal by the normalizing factor of Equation 2 below.Injection level information used to calculate Equation 2 below may betransferred to the power normalizer 345 via a signaling flow:

$\begin{matrix}{\text{Normalizing factor} = \left( \sqrt{\left( {1 + 10^{{\text{-Injection level}{(\text{dB})}}/10}} \right)} \right)^{- 1}} & \text{­­­(2)}\end{matrix}$

Assuming that the power levels of the core layer signal and the enhancedlayer signal are normalized to 1 when an enhanced layer signal S_(E) isinjected into a core layer signal S_(C) at a preset injection level, acombined signal may be expressed by S_(C) +αS_(E).

In this case, α is scaling factors corresponding to various injectionlevels. That is, the injection level controller 330 may correspond tothe scaling factor.

For example, when the injection level of an enhanced layer is 3 dB, acombined signal may be expressed by

$\text{S}_{\text{C}} + \sqrt{\frac{1}{2}}\text{S}_{\text{E}}\,.$

Since the power of a combined signal (a multiplexed signal) increasescompared to a core layer signal, the power normalizer 345 needs tomitigate the increase in power.

The output of the power normalizer 345 may be expressed by β(S_(C)+αS_(E)).

In this case, β is normalizing factors based on various injection levelsof the enhanced layer.

When the injection level of the enhanced layer is 3 dB, the power of thecombined signal is increased by 50% compared to that of the core layersignal. Accordingly, the output of the power normalizer 345 may beexpressed by

$\sqrt{\frac{2}{3}}\left( {\text{S}_{\text{C}} + \sqrt{\frac{1}{2}}\text{S}_{\text{E}}} \right).$

Table 1 below lists scaling factors α and normalizing factors β forvarious injection levels (CL: Core Layer, EL: Enhanced Layer). Therelationships among the injection level, the scaling factor α and thenormalizing factor β may be defined by Equation 3 below:

$\begin{matrix}\left\{ \begin{array}{l}{\alpha = 10^{(\frac{- \text{Injectionlevel}}{20})}} \\{\beta = \frac{1}{\sqrt{1 + \alpha^{2}}}}\end{array} \right) & \text{­­­(3)}\end{matrix}$

TABLE 1 EL Injection level relative to CL Scaling factor α Normalizingfactor β 3.0 dB 0.7079458 0.8161736 3.5 dB 0.6683439 0.8314061 4.0 dB0.6309573 0.8457262 4.5 dB 0.5956621 0.8591327 5.0 dB 0.56234130.8716346 5.5 dB 0.5308844 0.8832495 6.0 dB 0.5011872 0.8940022 6.5 dB0.4731513 0.9039241 7.0 dB 0.4466836 0.9130512 7.5 dB 0.42169650.9214231 8.0 dB 0.3981072 0.9290819 8.5 dB 0.3758374 0.9360712 9.0 dB0.3548134 0.9424353 9.5 dB 0.3349654 0.9482180 10.0 dB 0.31622780.9534626

That is, the power normalizer 345 corresponds to the normalizing factor,and reduces the power of the multiplexed signal by a level by which thecombiner 340 has increased the power.

In this case, each of the normalizing factor and the scaling factor maybe a rational number that is larger than 0 and smaller than 1.

In this case, the scaling factor may decrease as a reduction in powercorresponding to the injection level controller 330 becomes larger, andthe normalizing factor may increase as a reduction in powercorresponding to the injection level controller 330 becomes larger.

The power normalized signal passes through the time interleaver 350 fordistributing burst errors occurring over a channel.

In this case, the time interleaver 350 may be viewed as performinginterleaving that is applied to both the core layer signal and theenhanced layer signal. That is, the core layer and the enhanced layershare the time interleaver, thereby preventing the unnecessary use ofmemory and also reducing latency at the receiver.

Although will be described later in greater detail, the enhanced layersignal may correspond to enhanced layer data restored based oncancellation corresponding to the restoration of core layer datacorresponding to the core layer signal. The combiner 340 may combine oneor more extension layer signals having power levels lower than those ofthe core layer signal and the enhanced layer signal with the core layersignal and the enhanced layer signal.

Meanwhile, L1 signaling information including injection levelinformation is encoded by the signaling generation unit 360 includingsignaling-dedicated BICM. In this case, the signaling generation unit360 may receive injection level information IL INFO from the injectionlevel controller 330, and may generate an L1 signaling signal.

In L1 signaling, L1 refers to Layer-1 in the lowest layer of the ISO 7layer model. In this case, the L1 signaling may be included in apreamble.

In general, the L1 signaling may include an FFT size, a guard intervalsize, etc., i.e., the important parameters of the OFDM transmitter, achannel code rate, modulation information, etc., i.e., BICM importantparameters. This L1 signaling signal is combined with data signal into abroadcast signal frame.

The frame builder 370 generates a broadcast signal frame by combiningthe L1 signaling signal with a data signal. In this case, the framebuilder 370 may generate the broadcast signal frame including a preamblefor signaling size information of Physical Layer Pipes (PLPs) and timeinterleaver information shared by the core layer signal and the enhancedlayer signal, using the time interleaved signal. In this case, thebroadcast signal frame may further include a bootstrap.

In this case, the frame builder 370 may include a bootstrap generatorconfigured to generate the bootstrap, a preamble generator configured togenerate the preamble, and a super-imposed payload generator configuredto generate a super-imposed payload corresponding to thetime-interleaved signal.

In this case, the bootstrap may be shorter than the preamble, and have afixed-length.

In this case, the bootstrap may include a symbol representing astructure of the preamble, the symbol corresponding to a fixed-lengthbit string representing a combination of a modulation scheme/code rate,a FFT size, a guard interval length and a pilot pattern of the preamble.

In this case, the symbol may correspond to a lookup table in which apreamble structure corresponding to a second FFT size is allocated priorto a preamble structure corresponding to a first FFT size, the secondFFT size being less than the first FFT size when the modulationscheme/code rates are the same, and a preamble structure correspondingto a second guard interval length is allocated prior to a preamblestructure corresponding to a first guard interval length, the secondguard interval length being longer than the first guard interval lengthwhen the modulation scheme/code rates are the same and the FFT sizes arethe same.

The broadcast signal frame may be transmitted via the OFDM transmitterthat is robust to a multi-path and the Doppler phenomenon. In this case,the OFDM transmitter may be viewed as being responsible for thetransmission signal generation of the next generation broadcastingsystem.

In this case, the preamble may include a PLP identification informationfor identifying Physical Layer Pipes (PLPs); and a layer identificationinformation for identifying layers corresponding to division of layers.

In this case, the PLP identification information and the layeridentification information may be included in the preamble as fieldsdifferent from each other.

In this case, the time interleaver information may be included in thepreamble for each of the Physical Layer Pipes (PLPs) without checking acondition of a conditional statement corresponding to the layeridentification information (j).

In this case, the preamble may selectively include an injection levelinformation corresponding to the injection level controller for each ofthe Physical Layer Pipes (PLPs) based on a result of comparing (IF(j>0))the layer identification information with a predetermined value.

In this case, the preamble may include type information, start positioninformation and size information of the Physical Layer Pipes

In this case, the type information may be for identifying one among afirst type corresponding to a non-dispersed physical layer pipe and asecond type corresponding to a dispersed physical layer pipe.

In this case, the non-dispersed physical layer pipe may be assigned forcontiguous data cell indices, and the dispersed physical layer pipe mayinclude two or more subslices.

In this case, the type information may be selectively signaled accordingto a result of comparing the layer identification information with apredetermined value for each of the Physical Layer Pipes (PLPs).

In this case, the type information may be signaled only for the corelayer.

In this case, the start position information may be identical to anindex corresponding to the first data cell of the physical layer pipe.

In this case, the start position information may indicate the startposition of the physical layer pipe using cell addressing scheme.

In this case, the start position information may be included in thepreamble for each of the Physical Layer Pipes (PLPs) without checking acondition of a conditional statement corresponding to the layeridentification information.

In this case, the size information may be generated based on the numberof data cells assigned to the physical layer pipe.

In this case, the size information may be included in the preamble foreach of the Physical Layer Pipes (PLPs) without checking a condition ofa conditional statement corresponding to the layer identificationinformation.

FIG. 4 is a diagram showing an example of the structure of a broadcastsignal frame.

Referring to FIG. 4 , a broadcast signal frame includes the bootstrap410, the preamble 420 and the super-imposed payload 430.

The frame shown in FIG. 4 , may be included in the super-frame.

In this case, the broadcast signal frame may include at least one ofOFDM symbols. The broadcast signal frame may include a reference symbolor a pilot symbol.

The frame structure in which the Layered Division Multiplexing (LDM) isapplied includes the bootstrap 410, the preamble 420 and thesuper-imposed payload 430 as shown in FIG. 4 .

In this case, the bootstrap 410 and the preamble 420 may be seen as thetwo hierarchical preambles.

In this case, the bootstrap 410 may have a shorter length than thepreamble 420 for the fast acquisition and detection. In this case, thebootstrap 410 may have a fixed-length. In this case, the bootstrap mayinclude a fixed-length symbol. For example, the bootstrap 410 mayconsist of four OFDM symbols each of which has 0.5 ms length so that thebootstrap 410 may correspond to the fixed time length of 2 ms.

In this case, the bootstrap 410 may have a fixed bandwidth, and thepreamble 420 and the super-imposed payload 430 may have a variablebandwidth wider than the bootstrap 410.

The preamble 420 may transmit detailed signaling information using arobust LDPC code. In this case, the length of the preamble 420 can bevaried according to the signaling information.

In this case, both the bootstrap 410 and the payload 430 may be seen asa common signal which is shared by a plurality of layers.

The super-imposed payload 430 may correspond to a multiplexed signal ofat least two layer signals. In this case, the super-imposed payload 430may be generated by combining a core layer payload and an enhanced layerpayload at different power levels. In this case, the core layer payloadmay include am in-band signaling section. In this case, the in-bandsignaling section may include signaling information for the enhancedlayer service.

In this case, the bootstrap 410 may include a symbol representing apreamble structure.

In this case, the symbol which included in the bootstrap forrepresenting the preamble structure may be set as shown in the Table 2below.

TABLE 2 preamble_structure L1-Basic Mode FFT Size GI Length (samples)Pilot Pattern (DX) 0 L1-Basic Mode 1 8192 2048 3 1 L1-Basic Mode 1 81921536 4 2 L1-Basic Mode 1 8192 1024 3 3 L1-Basic Mode 1 8192 768 4 4L1-Basic Mode 1 16384 4096 3 5 L1-Basic Mode 1 16384 3648 4 6 L1-BasicMode 1 16384 2432 3 7 L1-Basic Mode 1 16384 1536 4 8 L1-Basic Mode 116384 1024 6 9 L1-Basic Mode 1 16384 768 8 10 L1-Basic Mode 1 32768 48643 11 L1-Basic Mode 1 32768 3648 3 12 L1-Basic Mode 1 32768 3648 8 13L1-Basic Mode 1 32768 2432 6 14 L1-Basic Mode 1 32768 1536 8 15 L1-BasicMode 1 32768 1024 12 16 L1-Basic Mode 1 32768 768 16 17 L1-Basic Mode 28192 2048 3 18 L1-Basic Mode 2 8192 1536 4 19 L1-Basic Mode 2 8192 10243 20 L1-Basic Mode 2 8192 768 4 21 L1-Basic Mode 2 16384 4096 3 22L1-Basic Mode 2 16384 3648 4 23 L1-Basic Mode 2 16384 2432 3 24 L1-BasicMode 2 16384 1536 4 25 L1-Basic Mode 2 16384 1024 6 26 L1-Basic Mode 216384 768 8 27 L1-Basic Mode 2 32768 4864 3 28 L1-Basic Mode 2 327683648 3 29 L1-Basic Mode 2 32768 3648 8 30 L1-Basic Mode 2 32768 2432 631 L1-Basic Mode 2 32768 1536 8 32 L1-Basic Mode 2 32768 1024 12 33L1-Basic Mode 2 32768 768 16 34 L1-Basic Mode 3 8192 2048 3 35 L1-BasicMode 3 8192 1536 4 36 L1-Basic Mode 3 8192 1024 3 37 L1-Basic Mode 38192 768 4 38 L1-Basic Mode 3 16384 4096 3 39 L1-Basic Mode 3 16384 36484 40 L1-Basic Mode 3 16384 2432 3 41 L1-Basic Mode 3 16384 1536 4 42L1-Basic Mode 3 16384 1024 6 43 L1-Basic Mode 3 16384 768 8 44 L1-BasicMode 3 32768 4864 3 45 L1-Basic Mode 3 32768 3648 3 46 L1-Basic Mode 332768 3648 8 47 L1-Basic Mode 3 32768 2432 6 48 L1-Basic Mode 3 327681536 8 49 L1-Basic Mode 3 32768 1024 12 50 L1-Basic Mode 3 32768 768 1651 L1-Basic Mode 4 8192 2048 3 52 L1-Basic Mode 4 8192 1536 4 53L1-Basic Mode 4 8192 1024 3 54 L1-Basic Mode 4 8192 768 4 55 L1-BasicMode 4 16384 4096 3 56 L1-Basic Mode 4 16384 3648 4 57 L1-Basic Mode 416384 2432 3 58 L1-Basic Mode 4 16384 1536 4 59 L1-Basic Mode 4 163841024 6 60 L1-Basic Mode 4 16384 768 8 61 L1-Basic Mode 4 32768 4864 3 62L1-Basic Mode 4 32768 3648 3 63 L1-Basic Mode 4 32768 3648 8 64 L1-BasicMode 4 32768 2432 6 65 L1-Basic Mode 4 32768 1536 8 66 L1-Basic Mode 432768 1024 12 67 L1-Basic Mode 4 32768 768 16 68 L1-Basic Mode 5 81922048 3 69 L1-Basic Mode 5 8192 1536 4 70 L1-Basic Mode 5 8192 1024 3 71L1-Basic Mode 5 8192 768 4 72 L1-Basic Mode 5 16384 4096 3 73 L1-BasicMode 5 16384 3648 4 74 L1-Basic Mode 5 16384 2432 3 75 L1-Basic Mode 516384 1536 4 76 L1-Basic Mode 5 16384 1024 6 77 L1-Basic Mode 5 16384768 8 78 L1-Basic Mode 5 32768 4864 3 79 L1-Basic Mode 5 32768 3648 3 80L1-Basic Mode 5 32768 3648 8 81 L1-Basic Mode 5 32768 2432 6 82 L1-BasicMode 5 32768 1536 8 83 L1-Basic Mode 5 32768 1024 12 84 L1-Basic Mode 532768 768 16 85 L1-Basic Mode 6 8192 2048 3 86 L1-Basic Mode 6 8192 15364 87 L1-Basic Mode 6 8192 1024 3 88 L1-Basic Mode 6 8192 768 4 89L1-Basic Mode 6 16384 4096 3 90 L1-Basic Mode 6 16384 3648 4 91 L1-BasicMode 6 16384 2432 3 92 L1-Basic Mode 6 16384 1536 4 93 L1-Basic Mode 616384 1024 6 94 L1-Basic Mode 6 16384 768 8 95 L1-Basic Mode 6 327684864 3 96 L1-Basic Mode 6 32768 3648 3 97 L1-Basic Mode 6 32768 3648 898 L1-Basic Mode 6 32768 2432 6 99 L1-Basic Mode 6 32768 1536 8 100L1-Basic Mode 6 32768 1024 12 101 L1-Basic Mode 6 32768 768 16 102L1-Basic Mode 7 8192 2048 3 103 L1-Basic Mode 7 8192 1536 4 104 L1-BasicMode 7 8192 1024 3 105 L1-Basic Mode 7 8192 768 4 106 L1-Basic Mode 716384 4096 3 107 L1-Basic Mode 7 16384 3648 4 108 L1-Basic Mode 7 163842432 3 109 L1-Basic Mode 7 16384 1536 4 110 L1-Basic Mode 7 16384 1024 6111 L1-Basic Mode 7 16384 768 8 112 L1-Basic Mode 7 32768 4864 3 113L1-Basic Mode 7 32768 3648 3 114 L1-Basic Mode 7 32768 3648 8 115L1-Basic Mode 7 32768 2432 6 116 L1-Basic Mode 7 32768 1536 8 117L1-Basic Mode 7 32768 1024 12 118 L1-Basic Mode 7 32768 768 16 119Reserved Reserved Reserved Reserved 120 Reserved Reserved ReservedReserved 121 Reserved Reserved Reserved Reserved 122 Reserved ReservedReserved Reserved 123 Reserved Reserved Reserved Reserved 124 ReservedReserved Reserved Reserved 125 Reserved Reserved Reserved Reserved 126Reserved Reserved Reserved Reserved 127 Reserved Reserved ReservedReserved

For example, a fixed-length symbol of 7-bit may be assigned forrepresenting the preamble structure shown in the Table 2.

The L1-Basic Mode 1, L1-Basic Mode 2 and L1-Basic Mode 3 in the Table 2may correspond to QPSK and 3/15 LDPC.

The L1 Basic Mode 4 in the Table 2 may correspond to 16-NUC (Non UniformConstellation) and 3/15 LDPC.

The L1 Basic Mode 5 in the Table 2 may correspond to 64-NUC (Non UniformConstellation) and 3/15 LDPC.

The L1-Basic Mode 6 and L1-Basic Mode 7 in the Table 2 may correspond to256-NUC (Non Uniform Constellation) and 3/15 LDPC. Hereafter, themodulation scheme/code rate represents a combination of a modulationscheme and a code rate such as QPSK and 3/15 LDPC.

The FFT size in the Table 2 may represent a size of Fast FourierTransform.

The GI length in the Table 2 may represent the Guard Interval Length,may represent a length of the guard interval which is not data in a timedomain. In this case, the guard interval is longer, the system is morerobust.

The Pilot Pattern in the Table 2 may represent Dx of the pilot pattern.Although it is not shown in the Table 2 explicitly, Dy may be all 1 inthe example of Table 2. For example, Dx = 3 may mean that one pilot forchannel estimation is included in x-axis direction in every threesymbols. For example, Dy = 1 may mean the pilot is included every timein y-axis direction.

As shown in the Table 2, the preamble structure corresponding to asecond modulation scheme/code rate which is more robust than a firstmodulation scheme/code rate may be allocated in the lookup table priorto the preamble structure corresponding to the first modulationscheme/code rate.

In this case, the being allocated prior to other preamble structure maymean being stored in the lookup table corresponding to a serial numberless than the serial number of the other preamble structure.

Furthermore, the preamble structure corresponding to a second FFT sizewhich is shorter than a first FFT size may be allocated in the lookuptable prior to the preamble structure corresponding to a first FFT sizein case of the same modulation scheme/code rate.

Furthermore, the preamble structure corresponding to a second guardinterval which is longer than a first guard interval may be allocated inthe lookup table prior to the preamble structure corresponding to thefirst guard interval in case of the same modulation scheme/code rate andthe same FFT size.

As shown in the Table 2, the setting of the order in which the preamblestructures are assigned in the lookup table may make the recognition ofthe preamble structure using the bootstrap more efficient.

FIG. 5 is a diagram showing an example of the receiving process of thebroadcast signal frame shown in FIG. 4 .

Referring to FIG. 5 , the bootstrap 510 is detected and demodulated, andthe signaling information is reconstructed by the demodulation of thepreamble 520 using the demodulated information.

The core layer data 530 is demodulated using the signaling informationand the enhanced layer signal is demodulated through the cancellationprocess corresponding to the core layer data. In this case, thecancellation corresponding to the core layer data will be described indetail later.

FIG. 6 is a diagram showing another example of the receiving process ofthe broadcast signal frame shown in FIG. 4 .

Referring to FIG. 6 , the bootstrap 610 is detected and demodulated, andthe signaling information is reconstructed by the demodulation of thepreamble 620 using the demodulated information.

The core layer data 630 is demodulated using the signaling information.In this case, the core layer data 630 includes in-band signaling section650. The in-band signaling section 650 includes signaling informationfor the enhanced layer service. The bandwidth is used more efficientlythrough the in-band signaling section 650. In this case, the in-bandsignaling section 650 may be included in the core layer which is morerobust than the enhanced layer.

The basic signaling information and the information for the core layerservice may be transferred through the preamble 620 and the signalinginformation for the enhanced layer service may be transferred throughthe in-band signaling section 650 in the example of the FIG. 6 .

The enhanced layer signal is demodulated through the cancellationprocess corresponding to the core layer data.

In this case, the signaling information may be L1 (Layer-1) signalinginformation. The L1 signaling information may include information forphysical layer parameters.

Referring to FIG. 4 , a broadcast signal frame includes an L1 signalingsignal and a data signal. For example, the broadcast signal frame may bean ATSC 3.0 frame.

FIG. 7 is a block diagram showing another example of the apparatus forgenerating broadcast signal frame shown in FIG. 1 .

Referring to FIG. 7 , it can be seen that an apparatus for generatingbroadcast signal frame multiplexes data corresponding to N (N is anatural number that is equal to or larger than 1) extension layerstogether in addition to core layer data and enhanced layer data.

That is, the apparatus for generating the broadcast signal frame in FIG.7 includes N extension layer BICM units 410,..., 430 and injection levelcontrollers 440,..., 460 in addition to a core layer BICM unit 310, anenhanced layer BICM unit 320, an injection level controller 330, acombiner 340, a power normalizer 345, a time interleaver 350, asignaling generation unit 360, and a frame builder 370.

The core layer BICM unit 310, enhanced layer BICM unit 320, injectionlevel controller 330, combiner 340, power normalizer 345, timeinterleaver 350, signaling generation unit 360 and frame builder 370shown in FIG. 7 have been described in detail with reference to FIG. 3 .

Each of the N extension layer BICM units 410,..., 430 independentlyperforms BICM encoding, and each of the injection level controllers440,..., 460 performs power reduction corresponding to a correspondingextension layer, thereby enabling a power reduced extension layer signalto be combined with other layer signals via the combiner 340.

In this case, each of the error correction encoders of the extensionlayer BICM units 410,..., 430 may be formed by connecting a BCH encoderand an LDPC encoder in series.

In particular, it is preferred that a reduction in power correspondingto each of the injection level controllers 440,..., 460 be higher thanthe reduction in power of the injection level controller 330. That is, alower one of the injection level controllers 330, 440,..., 460 shown inFIG. 7 may correspond to a larger reduction in power.

Injection level information provided by the injection level controllers330, 440 and 460 shown in FIG. 7 is included in the broadcast signalframe of the frame builder 370 via the signaling generation unit 360,and is then transmitted to the receiver. That is, the injection level ofeach layer is contained in the L1 signaling information and thentransferred to the receiver.

In the present invention, the adjustment of power may correspond toincreasing or decreasing the power of an input signal, and maycorrespond to increasing or decreasing the gain of an input signal.

The power normalizer 345 mitigates an increase in power caused by thecombination of a plurality of layer signals by means of the combiner340.

In the example shown in FIG. 7 , the power normalizer 345 may adjust thepower of a signal to appropriate magnitude by multiplying the magnitudeof a signal, into which the signals of the respective layers arecombined, by a normalizing factor by using Equation 4 below:

$\begin{matrix}\begin{array}{l}{\text{Normalizing factor} =} \\\left( \sqrt{\left( {1 + 10^{{\text{-Injectionlevel}\,\text{\#1}{(\text{dB})}}/10} + 10^{{\text{-Injectionlevel}\,\text{\#2}{(\text{dB})}}/10} + \cdots + 10^{{\text{-Injectionlevel}\,\text{\#}{(\text{N+1})}{(\text{dB})}}/10}} \right)} \right)^{- 1}\end{array} & \text{­­­(4)}\end{matrix}$

The time interleaver 350 performs interleaving equally applied to thesignals of the layers by interleaving the signals combined by thecombiner 340.

FIG. 8 is a block diagram showing still an example of the signaldemultiplexer shown in FIG. 1 .

Referring to FIG. 8 , a signal demultiplexer according to an embodimentof the present invention includes a time deinterleaver 510, ade-normalizer 1010, core layer BICM decoder 520, an enhanced layersymbol extractor 530, a de-injection level controller 1020, and anenhanced layer BICM decoder 540.

In this case, the signal demultiplexer shown in FIG. 8 may correspond tothe apparatus for generating the broadcast signal frame shown in FIG. 3.

The time deinterleaver 510 receives a received signal from an OFDMreceiver for performing operations, such as time/frequencysynchronization, channel estimation and equalization, and performs anoperation related to the distribution of burst errors occurring over achannel. In this case, the L1 signaling information is decoded by theOFDM receiver first, and is then used for the decoding of data. Inparticular, the injection level information of the L1 signalinginformation may be transferred to the de-normalizer 1010 and thede-injection level controller 1020. In this case, the OFDM receiver maydecode the received signal in the form of a broadcast signal frame, forexample, an ATSC 3.0 frame, may extract the data symbol part of theframe, and may provide the extracted data symbol part to the timedeinterleaver 510. That is, the time deinterleaver 510 distributes bursterrors occurring over a channel by performing deinterleaving whilepassing a data symbol therethrough.

The de-normalizer 1010 corresponds to the power normalizer of thetransmitter, and increases power by a level by which the powernormalizer has decreased the power. That is, the de-normalizer 1010divides the received signal by the normalizing factor of Equation 2.

Although the de-normalizer 1010 is illustrated as adjusting the power ofthe output signal of the time interleaver 510 in the example shown inFIG. 8 , the de-normalizer 1010 may be located before the timeinterleaver 510 so that power adjustment is performed beforeinterleaving in some embodiments.

That is, the de-normalizer 1010 may be viewed as being located before orafter the time interleaver 510 and amplifying the magnitude of a signalfor the purpose of the LLR calculation of the core layer symboldemapper.

The output of the time deinterleaver 510 (or the output of thede-normalizer 1010) is provided to the core layer BICM decoder 520, andthe core layer BICM decoder 520 restores core layer data.

In this case, the core layer BICM decoder 520 includes a core layersymbol demapper, a core layer bit deinterleaver, and a core layer errorcorrection decoder. The core layer symbol demapper calculates LLR valuesrelated to symbols, the core layer bit deinterleaver strongly mixes thecalculated LLR values with burst errors, and the core layer errorcorrection decoder corrects error occurring over a channel.

In this case, the core layer symbol demapper may calculate an LLR valuefor each bit using a predetermined constellation. In this case, theconstellation used by the core layer symbol mapper may vary depending onthe combination of the code rate and the modulation order that are usedby the transmitter.

In this case, the core layer bit deinterleaver may performdeinterleaving on calculated LLR values on an LDPC code word basis.

In particular, the core layer error correction decoder may output onlyinformation bits, or may output all bits in which information bits havebeen mixed with parity bits. In this case, the core layer errorcorrection decoder may output only information bits as core layer data,and may output all bits in which information bits have been mixed withparity bits to the enhanced layer symbol extractor 530.

The core layer error correction decoder may be formed by connecting acore layer LDPC decoder and a core layer BCH decoder in series. That is,the input of the core layer error correction decoder may be input to thecore layer LDPC decoder, the output of the core layer LDPC decoder maybe input to the core layer BCH decoder, and the output of the core layerBCH decoder may become the output of the core layer error correctiondecoder. In this case, the LDPC decoder performs LDPC decoding, and theBCH decoder performs BCH decoding.

Furthermore, the enhanced layer error correction decoder may be formedby connecting an enhanced layer LDPC decoder and an enhanced layer BCHdecoder in series. That is, the input of the enhanced layer errorcorrection decoder may be input to the enhanced layer LDPC decoder, theoutput of the enhanced layer LDPC decoder may be input to the enhancedlayer BCH decoder, and the output of the enhanced layer BCH decoder maybecome the output of the enhanced layer error correction decoder.

The enhanced layer symbol extractor 530 may receive all bits from thecore layer error correction decoder of the core layer BICM decoder 520,may extract enhanced layer symbols from the output signal of the timedeinterleaver 510 or de-normalizer 1010. In an embodiment, the enhancedlayer symbol extractor 530 may not be provided with all bits by theerror correction decoder of the core layer BICM decoder 520, but may beprovided with LDPC information bits or BCH information bits by the errorcorrection decoder of the core layer BICM decoder 520.

In this case, the enhanced layer symbol extractor 530 includes a buffer,a subtracter, a core layer symbol mapper, and a core layer bitinterleaver. The buffer stores the output signal of the timedeinterleaver 510 or de-normalizer 1010. The core layer bit interleaverreceives the all bits (information bits + parity bits) of the core layerBICM decoder, and performs the same core layer bit interleaving as thetransmitter. The core layer symbol mapper generates core layer symbols,which are the same as the transmitter, from the interleaved signal. Thesubtracter obtains enhanced layer symbols by subtracting the outputsignal of the core layer symbol mapper from the signal stored in thebuffer, and transfers the enhanced layer symbols to the de-injectionlevel controller 1020. In particular, when LDPC information bits areprovided, the enhanced layer symbol extractor 530 may further include acore layer LDPC encoder. Furthermore, when BCH information bits areprovided, the enhanced layer symbol extractor 530 may further includenot only a core layer LDPC encoder but also a core layer BCH encoder.

In this case, the core layer LDPC encoder, core layer BCH encoder, corelayer bit interleaver and core layer symbol mapper included in theenhanced layer symbol extractor 530 may be the same as the LDPC encoder,BCH encoder, bit interleaver and symbol mapper of the core layerdescribed with reference to FIG. 3 .

The de-injection level controller 1020 receives the enhanced layersymbols, and increases the power of the input signal by a level by whichthe injection level controller of the transmitter has decreased thepower. That is, the de-injection level controller 1020 amplifies theinput signal, and provides the amplified input signal to the enhancedlayer BICM decoder 540. For example, if at the transmitter, the powerused to combine the enhanced layer signal is lower than the power usedto combine the core layer signal by 3 dB, the de-injection levelcontroller 1020 functions to increase the power of the input signal by 3dB.

In this case, the de-injection level controller 1020 may be viewed asreceiving injection level information from the OFDM receiver andmultiplying an extracted enhanced layer signal by the enhanced layergain of Equation 5:

$\begin{matrix}{\text{Enhanced layer gain} = \left( \sqrt{10^{{\text{-Injectionlevel}{(\text{dB})}}/10}} \right)^{- 1}} & \text{­­­(5)}\end{matrix}$

The enhanced layer BICM decoder 540 receives the enhanced layer symbolwhose power has been increased by the de-injection level controller1020, and restores the enhanced layer data.

In this case, the enhanced layer BICM decoder 540 may include anenhanced layer symbol demapper, an enhanced layer bit deinterleaver, andan enhanced layer error correction decoder. The enhanced layer symboldemapper calculates LLR values related to the enhanced layer symbols,the enhanced layer bit deinterleaver strongly mixes the calculated LLRvalues with burst errors, and the enhanced layer error correctiondecoder corrects error occurring over a channel.

Although the enhanced layer BICM decoder 540 performs a task similar toa task that is performed by the core layer BICM decoder 520, theenhanced layer LDPC decoder generally performs LDPC decoding related toa code rate equal to or higher than 6/15.

For example, the core layer may use LDPC code having a code rate equalto or higher than 5/15, and the enhanced layer may use LDPC code havinga code rate equal to or higher than 6/15. In this case, in a receptionenvironment in which enhanced layer data can be decoded, core layer datamay be decoded using only a small number of LDPC decoding iterations.Using this characteristic, in the hardware of the receiver, a singleLDPC decoder is shared by the core layer and the enhanced layer, andthus the cost required to implement the hardware can be reduced. In thiscase, the core layer LDPC decoder may use only some time resources (LDPCdecoding iterations), and the enhanced layer LDPC decoder may use mosttime resources.

That is, the signal demultiplexer shown in FIG. 8 restores core layerdata first, leaves only the enhanced layer symbols by cancellation thecore layer symbols in the received signal symbols, and then restoresenhanced layer data by increasing the power of the enhanced layersymbols. As described with reference to FIGS. 3 and 5 , signalscorresponding to respective layers are combined at different powerlevels, and thus data restoration having the smallest error can beachieved only if restoration starts with a signal combined with thestrongest power.

Accordingly, in the example shown in FIG. 8 , the signal demultiplexermay include the time deinterleaver 510 configured to generate atime-deinterleaved signal by applying time deinterleaving to a receivedsignal; a de-normalizer 1010 configured to increase the power of thereceived signal or the time-deinterleaved signal by a levelcorresponding to a reduction in power by the power normalizer of thetransmitter; the core layer BICM decoder 520 configured to restore corelayer data from the signal power-adjusted by the de-normalizer 1010; theenhanced layer symbol extractor 530 configured to extract an enhancedlayer signal by performing cancellation, corresponding to the core layerdata, on the signal power-adjusted by the de-normalizer 1010 using theoutput signal of the core layer FEC decoder of the core layer BICMdecoder 520; a de-injection level controller 1020 configured to increasethe power of the enhanced layer signal by a level corresponding to areduction in power by the injection power level controller of thetransmitter; and an enhanced layer BICM decoder 540 configured torestore enhanced layer data using the output signal of the de-injectionlevel controller 1020.

In this case, the enhanced layer symbol extractor may receive all codewords from the core layer LDPC decoder of the core layer BICM decoder,and may immediately perform bit interleaving on the all code words.

In this case, the enhanced layer symbol extractor may receiveinformation bits from the core layer LDPC decoder of the core layer BICMdecoder, and may perform core layer LDPC encoding and then bitinterleaving on the information bits.

In this case, the enhanced layer symbol extractor may receiveinformation bits from the core layer BCH decoder of the core layer BICMdecoder, and may perform core layer BCH encoding and core layer LDPCencoding and then bit interleaving on the information bits.

In this case, the de-normalizer and the de-injection level controllermay receive injection level information IL INFO provided based on L1signaling, and may perform power control based on the injection levelinformation.

In this case, the core layer BICM decoder may have a bit rate lower thanthat of the enhanced layer BICM decoder, and may be more robust than theenhanced layer BICM decoder.

In this case, the de-normalizer may correspond to the reciprocal of thenormalizing factor.

In this case, the de-injection level controller may correspond to thereciprocal of the scaling factor.

In this case, the enhanced layer data may be restored based oncancellation corresponding to the restoration of core layer datacorresponding to the core layer signal.

In this case, the signal demultiplexer further may include one or moreextension layer symbol extractors each configured to extract anextension layer signal by performing cancellation corresponding toprevious layer data; one or more de-injection level controllers eachconfigured to increase the power of the extension layer signal by alevel corresponding to a reduction in power by the injection levelcontroller of the transmitter; and one or more extension layer BICMdecoders configured to restore one or more pieces of extension layerdata using the output signals of the one or more de-injection levelcontrollers.

From the configuration shown in FIG. 8 , it can be seen that a signaldemultiplexing method according to an embodiment of the presentinvention includes generating a time-deinterleaved signal by applyingtime deinterleaving to a received signal; increasing the power of thereceived signal or the time-deinterleaved signal by a levelcorresponding to a reduction in power by the power normalizer of thetransmitter; restoring core layer data from the power-adjusted signal;extracting an enhanced layer signal by performing cancellation,corresponding to the core layer data, on the power-adjusted signal;increasing the power of the enhanced layer signal by a levelcorresponding to a reduction in power by the injection power levelcontroller of the transmitter; and restoring enhanced layer data usingthe enhanced layer data.

In this case, extracting the enhanced layer signal may include receivingall code words from the core layer LDPC decoder of the core layer BICMdecoder, and immediately performing bit interleaving on the all codewords.

In this case, extracting the enhanced layer signal may include receivinginformation bits from the core layer LDPC decoder of the core layer BICMdecoder, and performing core layer LDPC encoding and then bitinterleaving on the information bits.

In this case, extracting the enhanced layer signal may include receivinginformation bits from the core layer BCH decoder of the core layer BICMdecoder, and performing core layer BCH encoding and core layer LDPCencoding and then bit interleaving on the information bits.

FIG. 9 is a block diagram showing an example of the core layer BICMdecoder 520 and the enhanced layer symbol extractor 530 shown in FIG. 8.

Referring to FIG. 9 , the core layer BICM decoder 520 includes a corelayer symbol demapper, a core layer bit deinterleaver, a core layer LDPCdecoder, and a core layer BCH decoder.

That is, in the example shown in FIG. 9 , the core layer errorcorrection decoder includes the core layer LDPC decoder and the corelayer BCH decoder.

Furthermore, in the example shown in FIG. 9 , the core layer LDPCdecoder provides all code words, including parity bits, to the enhancedlayer symbol extractor 530. That is, although the LDPC decoder generallyoutputs only the information bits of all the LDPC code words, the LDPCdecoder may output all the code words.

In this case, although the enhanced layer symbol extractor 530 may beeasily implemented because it does not need to include a core layer LDPCencoder or a core layer BCH encoder, there is a possibility that aresidual error may remain in the LDPC code parity part.

FIG. 10 is a block diagram showing another example of the core layerBICM decoder 520 and the enhanced layer symbol extractor 530 shown inFIG. 8 .

Referring to FIG. 10 , the core layer BICM decoder 520 includes a corelayer symbol demapper, a core layer bit deinterleaver, a core layer LDPCdecoder, and a core layer BCH decoder.

That is, in the example shown in FIG. 10 , the core layer errorcorrection decoder includes the core layer LDPC decoder and the corelayer BCH decoder.

Furthermore, in the example shown in FIG. 10 , the core layer LDPCdecoder provides information bits, excluding parity bits, to theenhanced layer symbol extractor 530.

In this case, although the enhanced layer symbol extractor 530 does notneed to include a core layer BCH encoder, it must include a core layerLDPC encoder.

A residual error that may remain in the LDPC code parity part may beeliminated more desirably in the example shown in FIG. 10 than in theexample shown in FIG. 9 .

FIG. 11 is a block diagram showing still another example of the corelayer BICM decoder 520 and the enhanced layer symbol extractor 530 shownin FIG. 8 .

Referring to FIG. 11 , the core layer BICM decoder 520 includes a corelayer symbol demapper, a core layer bit deinterleaver, a core layer LDPCdecoder, and a core layer BCH decoder.

That is, in the example shown in FIG. 11 , the core layer errorcorrection decoder includes the core layer LDPC decoder and the corelayer BCH decoder.

In the example shown in FIG. 11 , the output of the core layer BCHdecoder corresponding to core layer data is provided to the enhancedlayer symbol extractor 530.

In this case, although the enhanced layer symbol extractor 530 has highcomplexity because it must include both a core layer LDPC encoder and acore layer BCH encoder, it guarantees higher performance than those inthe examples of FIGS. 9 and 10 .

FIG. 12 is a block diagram showing another example of the signaldemultiplexer shown in FIG. 1 .

Referring to FIG. 12 , a signal demultiplexer according to an embodimentof the present invention includes a time deinterleaver 510, ade-normalizer 1010, a core layer BICM decoder 520, an enhanced layersymbol extractor 530, an enhanced layer BICM decoder 540, one or moreextension layer symbol extractors 650 and 670, one or more extensionlayer BICM decoders 660 and 680, and de-injection level controllers1020, 1150 and 1170.

In this case, the signal demultiplexer shown in FIG. 12 may correspondto the apparatus for generating broadcast signal frame shown in FIG. 7 .

The time deinterleaver 510 receives a received signal from an OFDMreceiver for performing operations, such as synchronization, channelestimation and equalization, and performs an operation related to thedistribution of burst errors occurring over a channel. In this case, L1signaling information may be decoded by the OFDM receiver first, andthen may be used for data decoding. In particular, the injection levelinformation of the L1 signaling information may be transferred to thede-normalizer 1010 and the de-injection level controllers 1020, 1150 and1170.

In this case, the de-normalizer 1010 may obtain the injection levelinformation of all layers, may obtain a de-normalizing factor usingEquation 6 below, and may multiply the input signal with thede-normalizing factor:

$\begin{matrix}\begin{array}{l}{\text{De}\mspace{6mu}\text{-}\mspace{6mu}\text{normalizing factor} = \left( \text{normalizing factor} \right)^{\text{-1}} =} \\\left( \sqrt{\left( {1 + 10^{{\text{-Injectionlevel}\,\text{\#1}{(\text{dB})}}/10} + 10^{{\text{-Injectionlevel}\,\text{\#2}{(\text{dB})}}/10} + \cdots + 10^{{\text{-Injectionlevel}\,\text{\#}{(\text{N+1})}{(\text{dB})}}/10}} \right)} \right)\end{array} & \text{­­­(6)}\end{matrix}$

That is, the de-normalizing factor is the reciprocal of the normalizingfactor expressed by Equation 4 above.

In an embodiment, when the N1 signaling includes not only injectionlevel information but also normalizing factor information, thede-normalizer 1010 may simply obtain a de-normalizing factor by takingthe reciprocal of a normalizing factor without the need to calculate thede-normalizing factor using an injection level.

The de-normalizer 1010 corresponds to the power normalizer of thetransmitter, and increases power by a level by which the powernormalizer has decreased the power.

Although the de-normalizer 1010 is illustrated as adjusting the power ofthe output signal of the time interleaver 510 in the example shown inFIG. 12 , the de-normalizer 1010 may be located before the timeinterleaver 510 so that power adjustment can be performed beforeinterleaving in an embodiment.

That is, the de-normalizer 1010 may be viewed as being located before orafter the time interleaver 510 and amplifying the magnitude of a signalfor the purpose of the LLR calculation of the core layer symboldemapper.

The output of the time deinterleaver 510 (or the output of thede-normalizer 1010) is provided to the core layer BICM decoder 520, andthe core layer BICM decoder 520 restores core layer data.

In this case, the core layer BICM decoder 520 includes a core layersymbol demapper, a core layer bit deinterleaver, and a core layer errorcorrection decoder. The core layer symbol demapper calculates LLR valuesrelated to symbols, the core layer bit deinterleaver strongly mixes thecalculated LLR values with burst errors, and the core layer errorcorrection decoder corrects error occurring over a channel.

In particular, the core layer error correction decoder may output onlyinformation bits, or may output all bits in which information bits havebeen combined with parity bits. In this case, the core layer errorcorrection decoder may output only information bits as core layer data,and may output all bits in which information bits have been combinedwith parity bits to the enhanced layer symbol extractor 530.

The core layer error correction decoder may be formed by connecting acore layer LDPC decoder and a core layer BCH decoder in series. That is,the input of the core layer error correction decoder may be input to thecore layer LDPC decoder, the output of the core layer LDPC decoder maybe input to the core layer BCH decoder, and the output of the core layerBCH decoder may become the output of the core layer error correctiondecoder. In this case, the LDPC decoder performs LDPC decoding, and theBCH decoder performs BCH decoding.

The enhanced layer error correction decoder may be also formed byconnecting an enhanced layer LDPC decoder and an enhanced layer BCHdecoder in series. That is, the input of the enhanced layer errorcorrection decoder may be input to the enhanced layer LDPC decoder, theoutput of the enhanced layer LDPC decoder may be input to the enhancedlayer BCH decoder, and the output of the enhanced layer BCH decoder maybecome the output of the enhanced layer error correction decoder.

Moreover, the extension layer error correction decoder may be alsoformed by connecting an extension layer LDPC decoder and an extensionlayer BCH decoder in series. That is, the input of the extension layererror correction decoder may be input to the extension layer LDPCdecoder, the output of the extension layer LDPC decoder may be input tothe extension layer BCH decoder, and the output of the extension layerBCH decoder may become the output of the extension layer errorcorrection decoder.

In particular, the tradeoff between the complexity of implementation,regarding which of the outputs of the error correction decoders will beused, which has been described with reference to FIGS. 9, 10 and 11 ,and performance is applied to not only the core layer BICM decoder 520and enhanced layer symbol extractor 530 of FIG. 12 but also theextension layer symbol extractors 650 and 670 and the extension layerBICM decoders 660 and 680.

The enhanced layer symbol extractor 530 may receive the all bits fromthe core layer BICM decoder 520 of the core layer error correctiondecoder, and may extract enhanced layer symbols from the output signalof the time deinterleaver 510 or the denormalizer 1010. In anembodiment, the enhanced layer symbol extractor 530 may not receive allbits from the error correction decoder of the core layer BICM decoder520, but may receive LDPC information bits or BCH information bits.

In this case, the enhanced layer symbol extractor 530 includes a buffer,a subtracter, a core layer symbol mapper, and a core layer bitinterleaver. The buffer stores the output signal of the timedeinterleaver 510 or de-normalizer 1010. The core layer bit interleaverreceives the all bits (information bits + parity bits) of the core layerBICM decoder, and performs the same core layer bit interleaving as thetransmitter. The core layer symbol mapper generates core layer symbols,which are the same as the transmitter, from the interleaved signal. Thesubtracter obtains enhanced layer symbols by subtracting the outputsignal of the core layer symbol mapper from the signal stored in thebuffer, and transfers the enhanced layer symbols to the de-injectionlevel controller 1020.

In this case, the core layer bit interleaver and core layer symbolmapper included in the enhanced layer symbol extractor 530 may be thesame as the core layer bit interleaver and the core layer symbol mappershown in FIG. 7 .

The de-injection level controller 1020 receives the enhanced layersymbols, and increases the power of the input signal by a level by whichthe injection level controller of the transmitter has decreased thepower. That is, the de-injection level controller 1020 amplifies theinput signal, and provides the amplified input signal to the enhancedlayer BICM decoder 540.

The enhanced layer BICM decoder 540 receives the enhanced layer symbolwhose power has been increased by the de-injection level controller1020, and restores the enhanced layer data.

In this case, the enhanced layer BICM decoder 540 may include anenhanced layer symbol demapper, an enhanced layer bit deinterleaver, andan enhanced layer error correction decoder. The enhanced layer symboldemapper calculates LLR values related to the enhanced layer symbols,the enhanced layer bit deinterleaver strongly mixes the calculated LLRvalues with burst errors, and the enhanced layer error correctiondecoder corrects error occurring over a channel.

In particular, the enhanced layer error correction decoder may outputonly information bits, and may output all bits in which information bitshave been combined with parity bits. In this case, the enhanced layererror correction decoder may output only information bits as enhancedlayer data, and may output all bits in which information bits have beenmixed with parity bits to the extension layer symbol extractor 650.

The extension layer symbol extractor 650 receives all bits from theenhanced layer error correction decoder of the enhanced layer BICMdecoder 540, and extracts extension layer symbols from the output signalof the de-injection level controller 1020.

In this case, the de-injection level controller 1020 may amplify thepower of the output signal of the subtracter of the enhanced layersymbol extractor 530.

In this case, the extension layer symbol extractor 650 includes abuffer, a subtracter, an enhanced layer symbol mapper, and an enhancedlayer bit interleaver. The buffer stores the output signal of thede-injection level controller 1020. The enhanced layer bit interleaverreceives the all bits information (bits + parity bits) of the enhancedlayer BICM decoder, and performs enhanced layer bit interleaving that isthe same as that of the transmitter. The enhanced layer symbol mappergenerates enhanced layer symbols, which are the same as those of thetransmitter, from the interleaved signal. The subtracter obtainsextension layer symbols by subtracting the output signal of the enhancedlayer symbol mapper from the signal stored in the buffer, and transfersthe extension layer symbols to the extension layer BICM decoder 660.

In this case, the enhanced layer bit interleaver and the enhanced layersymbol mapper included in the extension layer symbol extractor 650 maybe the same as the enhanced layer bit interleaver and the enhanced layersymbol mapper shown in FIG. 7 .

The de-injection level controller 1150 increases power by a level bywhich the injection level controller of a corresponding layer hasdecreased the power at the transmitter.

In this case, the de-injection level controller may be viewed asperforming the operation of multiplying the extension layer gain ofEquation 7 below. In this case, a 0-th injection level may be consideredto be 0 dB:

$\begin{matrix}\begin{array}{l}\text{n - th extension layer gain =} \\\frac{10^{{\text{-Injectionlevel}\,\text{\#}{(\text{n-1})}{(\text{dB})}}/10}}{10^{{\text{-Injectionlevel}\,\text{\#n}{(\text{dB})}}/10}}\end{array} & \text{­­­(7)}\end{matrix}$

The extension layer BICM decoder 660 receives the extension layersymbols whose power has been increased by the de-injection levelcontroller 1150, and restores extension layer data.

In this case, the extension layer BICM decoder 660 may include anextension layer symbol demapper, an extension layer bit deinterleaver,and an extension layer error correction decoder. The extension layersymbol demapper calculates LLR values related to the extension layersymbols, the extension layer bit deinterleaver strongly mixes thecalculated LLR values with burst errors, and the extension layer errorcorrection decoder corrects error occurring over a channel.

In particular, each of the extension layer symbol extractor and theextension layer BICM decoder may include two or more extractors ordecoders if two or more extension layers are present.

That is, in the example shown in FIG. 12 , the extension layer errorcorrection decoder of the extension layer BICM decoder 660 may outputonly information bits, and may output all bits in which information bitshave been combined with parity bits. In this case, the extension layererror correction decoder outputs only information bits as extensionlayer data, and may output all bits in which information bits have beenmixed with parity bits to the subsequent extension layer symbolextractor 670.

The configuration and operation of the extension layer symbol extractor670, the extension layer BICM decoder 680 and the de-injection levelcontroller 1170 can be easily understood from the configuration andoperation of the above-described extension layer symbol extractor 650,extension layer BICM decoder 660 and de-injection level controller 1150.

A lower one of the de-injection level controllers 1020, 1150 and 1170shown in FIG. 12 may correspond to a larger increase in power. That is,the de-injection level controller 1150 may increase power more than thede-injection level controller 1020, and the de-injection levelcontroller 1170 may increase power more than the de-injection levelcontroller 1150.

It can be seen that the signal demultiplexer shown in FIG. 12 restorescore layer data first, restores enhanced layer data using thecancellation of core layer symbols, and restores extension layer datausing the cancellation of enhanced layer symbols. Two or more extensionlayers may be provided, in which case restoration starts with anextension layer combined at a higher power level.

FIG. 13 is a diagram showing in an increase in power attributable to thecombination of a core layer signal and an enhanced layer signal.

Referring to FIG. 13 , it can be seen that when a multiplexed signal isgenerated by combining a core layer signal with an enhanced layer signalwhose power has been reduced by an injection level, the power level ofthe multiplexed signal is higher than the power level of the core layersignal or the enhanced layer signal.

In this case, the injection level that is adjusted by the injectionlevel controllers shown in FIGS. 3 and 7 may be adjusted from 0 dB to25.0 dB in steps of 0.5 dB or 1 dB. When the injection level is 3.0 dB,the power of the enhanced layer signal is lower than that of the corelayer signal by 3 dB. When the injection level is 10.0 dB, the power ofthe enhanced layer signal is lower than that of the core layer signal by10 dB. This relationship may be applied not only between a core layersignal and an enhanced layer signal but also between an enhanced layersignal and an extension layer signal or between extension layer signals.

The power normalizers shown in FIGS. 3 and 7 may adjust the power levelafter the combination, thereby solving problems, such as the distortionof the signal, that may be caused by an increase in power attributableto the combination.

FIG. 14 is an operation flowchart showing a method of generatingbroadcast signal frame according to an embodiment of the presentinvention.

Referring to FIG. 14 , in the method according to the embodiment of thepresent invention, BICM is applied to core layer data at step S1210.

Furthermore, in the method according to the embodiment of the presentinvention, BICM is applied to enhanced layer data at step S1220.

The BICM applied at step S1220 may be different from the BICM applied tostep S1210. In this case, the BICM applied at step S1220 may be lessrobust than the BICM applied to step S1210. In this case, the bit rateof the BICM applied at step S1220 may be less robust than that of theBICM applied to step S1210.

In this case, an enhanced layer signal may correspond to the enhancedlayer data that is restored based on cancellation corresponding to therestoration of the core layer data corresponding to a core layer signal.

Furthermore, in the method according to the embodiment of the presentinvention, a power-reduced enhanced layer signal is generated byreducing the power of the enhanced layer signal at step S1230.

In this case, at step S1230, an injection level may be changed from 00dB to 25.0 dB in steps of 0.5 dB or 1 dB.

Furthermore, in the method according to the embodiment of the presentinvention, a multiplexed signal is generated by combining the core layersignal and the power-reduced enhanced layer signal at step S1240.

That is, at step S1240, the core layer signal and the enhanced layersignal are combined at different power levels so that the power level ofthe enhanced layer signal is lower than the power level of the corelayer signal.

In this case, at step S1240, one or more extension layer signals havinglower power levels than the core layer signal and the enhanced layersignal may be combined with the core layer signal and the enhanced layersignal.

Furthermore, in the method according to the embodiment of the presentinvention, the power of the multiplexed signal is reduced at step S1250.

In this case, at step S1250, the power of the multiplexed signal may bereduced to the power of the core layer signal. In this case, at stepS1250, the power of the multiplexed signal may be reduced by a level bywhich the power has been increased at step S1240.

Furthermore, in the method according to the embodiment of the presentinvention, a time-interleaved signal is generated by performing timeinterleaving that is applied to both the core layer signal and theenhanced layer signal is performed at step S1260.

Furthermore, in the method according to the embodiment of the presentinvention, a broadcast signal frame including a preamble for signalingtype information and size information of Physical Layer Pipes (PLPs) andtime interleaver information shared by the core layer signal and theenhanced layer signal is generated using the time-interleaved signal atstep S1270.

In this case, the step S1270 may include generating the bootstrap;generating the preamble; and generating a super-imposed payloadcorresponding to the time-interleaved signal.

In this case, the preamble may include a PLP identification informationfor identifying Physical Layer Pipes (PLPs); and a layer identificationinformation for identifying layers corresponding to division of layers.

In this case, the PLP identification information and the layeridentification information may be included in the preamble as fieldsdifferent from each other.

In this case, the time interleaver information may be included in thepreamble for each of the Physical Layer Pipes (PLPs) without checking acondition of a conditional statement corresponding to the layeridentification information (j).

In this case, the preamble may selectively include an injection levelinformation corresponding to the injection level controller for each ofthe Physical Layer Pipes (PLPs) based on a result of comparing (IF(j>0))the layer identification information with a predetermined value.

In this case, the bootstrap may be shorter than the preamble, and have afixed-length.

In this case, the bootstrap may include a symbol representing astructure of the preamble, the symbol corresponding to a fixed-lengthbit string representing a combination of a modulation scheme/code rate,a FFT size, a guard interval length and a pilot pattern of the preamble.

In this case, the symbol may correspond to a lookup table in which apreamble structure corresponding to a second FFT size is allocated priorto a preamble structure corresponding to a first FFT size, the secondFFT size being less than the first FFT size when the modulationscheme/code rates are the same, and a preamble structure correspondingto a second guard interval length is allocated prior to a preamblestructure corresponding to a first guard interval length, the secondguard interval length being longer than the first guard interval lengthwhen the modulation scheme/code rates are the same and the FFT sizes arethe same.

In this case, the broadcast signal frame may be an ATSC 3.0 frame.

In this case, the L1 signaling information may include injection levelinformation and/or normalizing factor information.

In this case, the preamble may include type information, start positioninformation and size information of the Physical Layer Pipes

In this case, the type information may be for identifying one among afirst type corresponding to a non-dispersed physical layer pipe and asecond type corresponding to a dispersed physical layer pipe.

In this case, the non-dispersed physical layer pipe may be assigned forcontiguous data cell indices, and the dispersed physical layer pipe mayinclude two or more subslices.

In this case, the type information may be selectively signaled accordingto a result of comparing the layer identification information with apredetermined value for each of the Physical Layer Pipes (PLPs).

In this case, the type information may be signaled only for the corelayer.

In this case, the start position information may be identical to anindex corresponding to the first data cell of the physical layer pipe.

In this case, the start position information may indicate the startposition of the physical layer pipe using cell addressing scheme.

In this case, the start position information may be included in thepreamble for each of the Physical Layer Pipes (PLPs) without checking acondition of a conditional statement corresponding to the layeridentification information.

In this case, the size information may be generated based on the numberof data cells assigned to the physical layer pipe.

In this case, the size information may be included in the preamble foreach of the Physical Layer Pipes (PLPs) without checking a condition ofa conditional statement corresponding to the layer identificationinformation.

Although not explicitly shown in FIG. 14 , the method may furtherinclude the step of generating signaling information including injectionlevel information corresponding to step S1230. In this case, thesignaling information may be L1 signaling information.

The method of generating broadcast signal frame shown in FIG. 14 maycorrespond to step S210 shown in FIG. 2 .

FIG. 15 is a diagram showing a structure of a super-frame which includesbroadcast signal frames according to an embodiment of the presentinvention.

Referring to FIG. 15 , the super-frame based on the Layered DivisionMultiplexing (LDM) configures at least one of frame, and each frameconfigures at least one of OFDM symbol.

In this case, each OFDM symbol may start with at least one preamblesymbol. Moreover, the frame may include a reference symbol or a pilotsymbol.

The super-frame 1510 illustrated in FIG. 15 , may include an LDM frame1520, a single layer frame without LDM 1530 and a Future Extension Frame(FEF) for future extensibility 1540 and may be configured using TimeDivision Multiplexing (TDM).

The LDM frame 1520 may include an Upper Layer (UL) 1553 and a LowerLayer (LL) 1555 when two layers are applied.

In this case, the upper layer 1553 may correspond to the core layer andthe lower layer 1555 may correspond to the enhanced layer.

In this case, the LDM frame 1520 which includes the upper layer 1553 andthe lower layer 1555 may a bootstrap 1552 and a preamble 1551.

In this case, the upper layer data and the lower layer data may sharethe time interleaver for reducing complexity and memory size and may usethe same frame length and FFT size.

Moreover, the single-layer frame 1530 may include the bootstrap 1562 andthe preamble 1561.

In this case, the single-layer frame 1530 may use a FFT size, timeinterleaver and frame length different from the LDM frame 1520. In thiscase, the single-layer frame 1530 may be multiplexed with the LDM frame1520 in the super-frame 1510 based on TDM scheme.

FIG. 16 is a diagram showing an example of an LDM frame using LDM of twolayers and multiple-physical layer pipes.

Referring to FIG. 16 , the LDM frame starts with a bootstrap signalincluding version information of the system or general signalinginformation. The L1 signaling signal which includes code rate,modulation information, number information of physical layer pipes mayfollow the bootstrap as a preamble.

The common Physical Layer Pipe (PLP) in a form of burst may betransferred following the preamble (L1 SIGNAL). In this case, the commonphysical layer pipe may transfer data which can be shared with otherphysical layer pipes in the frame.

The Multiple-Physical Layer Pipes for servicing broadcasting signalswhich are different from each other may be transferred using LDM schemeof two layers. In this case, the service (720 p or 1080 p HD, etc.)which needs robust reception performance such as indoor/mobile may usethe core layer (upper layer) data physical layer pipes. In this case,the fixed reception service (4K-UHD or multiple HD, etc.) which needshigh transfer rate may use the enhanced layer (lower layer) dataphysical layer pipes.

If the multiple physical layer pipes are layer-division-multiplexed, itcan be seen that the total number of physical layer pipes increases.

In this case, the core layer data physical layer pipe and the enhancedlayer data physical layer pipe may share the time interleaver forreducing complexity and memory size. In this case, the core layer dataphysical layer pipe and the enhanced layer data physical layer pipe mayhave the same physical layer pipe size (PLP size), and may have physicallayer pipe sizes different from each other.

In accordance with the embodiments, the layer-divided PLPs may have PLPsizes different from one another, and information for identifying thestat position of the PLP or information for identifying the size of thePLP may be signaled.

FIG. 17 is a diagram showing another example of an LDM frame using LDMof two layers and multiple-physical layer pipes.

Referring to FIG. 17 , the LDM frame may include the common physicallayer pipe after the bootstrap and the preamble (L1 SIGNAL). The corelayer data physical layer pipes and the enhanced layer data physicallayer pipes may be transferred using two-layer LDM scheme after thecommon physical layer pipe.

In particular, the core layer data physical layer pipes and the enhancedlayer data physical layer pipes of FIG. 17 may correspond to one typeamong type 1 and type 2. The type 1 and the type 2 may be defined asfollows:

-   Type 1 PLP    -   It is transferred after the common PLP if the common PLP exists    -   It is transferred in a form of burst (one slice) in the frame-   Type 2 PLP    -   It is transferred after the type 1 PLP if the type 1 PLP exists    -   It is transferred in a form of two or more sub-slices in the        frame    -   The time diversity and the power consumption increase as the        number of sub-slices increases

In this case, the type 1 PLP may correspond to a non-dispersed PLP, andthe type 2 PLP may correspond to a dispersed PLP. In this case, thenon-dispersed PLP may assigned for contiguous data cell indices. In thiscase, the dispersed PLP may assigned to two or more subslices.

FIG. 18 is a diagram showing an application example of LDM frame usingLDM of two layers and multiple physical layer pipes.

Referring to FIG. 18 , the common physical layer pipe (PLP(1,1)) may beincluded after the bootstrap and the preamble in the LDM frame. The dataphysical layer pipe (PLP(2,1)) for robust audio service may be includedin the LDM frame using the time-division scheme.

Moreover, the core layer data physical layer pipe (PLP(3,1)) formobile/indoor service (720 p or 1080 p HD) and the enhanced layer dataphysical layer pipe (PLP(3,2)) for high data rate service (4K-UHD ormultiple HD) may be transferred using 2-layer LDM scheme.

FIG. 19 is a diagram showing another application example of an LDM frameusing LDM of two layers and multiple physical layer pipes.

Referring to FIG. 19 , the LDM frame may include the bootstrap, thepreamble, the common physical layer pipe (PLP(1,1)). In this case, therobust audio service and mobile/indoor service (720 p or 1080 p HD) maybe transferred using core layer data physical layer pipes(PLP(2,1),PLP(3,1)), and the high data rate service (4K-UHD or multipleHD) may be transferred using the enhanced layer data physical layerpipes (PLP(2,2),PLP(3,2)).

In this case, the core layer data physical layer pipe and the enhancedlayer data physical layer pipe may use the same time interleaver.

In this case, the physical layer pipes (PLP(2,2),PLP(3,2)) which providethe same service may be identified using the PLP_GROUP_ID indicating thesame PLP group.

In accordance with the embodiment, the service can be identified usingthe start position and the size of each physical layer pipe withoutPLP_GROUP_ID when the physical layer pipes which have sizes differentfrom each other for different LDM layers are used.

Although multiple physical layer pipes and layers corresponding to thelayered division multiplexing are identified by PLP(i,j) in FIG. 18 andFIG. 19 , the PLP identification information and the layeridentification information may be signaled as fields different from eachother.

In accordance with the embodiment, different layers may use PLPs havingdifferent sizes. In this case, each service may be identified using thePLP identifier.

The PLP start position and the PLP size may be signaled for each PLPwhen PLPs having different sizes are used for different layers.

The following pseudo code is for showing an example of fields includedin the preamble according to an embodiment of the present invention. Thefollowing pseudo code may be included in the L1 signaling information ofthe preamble.

[Pseudo Code] SUB_SLICES_PER_FRAME (15 bits) NUM_PLP (8 bits) NUM_AUX (4bits) AUX_CONFIG_RFU (8 bits) for i=0.. NUM_RF-1 { RF_IDX (3 bits)FREQUENCY (32 bits) } IF S2==‘xxx1’ { FEF_TYPE (4 bits) FEF_LENGTH (22bits) FEF_INTERVAL (8 bits) } for i=0 .. NUM_PLP-1 { NUM_LAYER (2 \~3bits) for j=0 .. NUM_LAYER-1{ / * Signaling for each layer */ PLP_ID (i,j) (8 bits) PLP_GROUP_ID (8 bits) PLP_TYPE (3 bits) PLP_PAYLOAD_TYPE (5bits) PLP_COD (4 bits) PLP_MOD (3 bits) PLP_SSD (1 bit) PLP_FEC_TYPE (2bits) PLP_NUM_BLOCKS_MAX (10 bits) IN_BAND_A_FLAG (1 bit) IN_BAND_B_FLAG(1 bit) PLP_MODE (2 bits) STATIC_PADDING_FLAG (1 bit) IF (j > 0)LL_INJECTION_LEVEL (3 \~8 bits) } / * End of NUM_LAYER loop */ / *Common signaling for all layers */ FF_FLAG (1 bit) FIRST_RF_IDX (3 bits)FIRST_FRAME_IDX (8 bits) FRAME_INTERVAL (8 bits) TIME_IL_LENGTH (8 bits)TIME_IL_TYPE (1 bit) RESERVED_1 (11 bits) STATIC_FLAG (1 bit) PLP_START(24 bits) PLP_SIZE (24 bits) } / * End of NUM_PLP loop */ FEF_LENGTH_MSB(2 bits) RESERVED_2 (30 bits) for i=0 .. NUM_AUX-1 { AUX_STREAM_TYPE (4bits) AUX_PRIVATE_CONF (28 bits) }

The NUM_LAYER may correspond to two bits or three bits in the abovepseudo code. In this case, the NUM_LAYER may be a field for identifyingthe number of layers in each PLP which is divided in time. In this case,the NUM_LAYER may be defined in the NUM_PLP loop so that the number ofthe layers can be different for each PLP which is divided in time.

The LL_INJECTION_LEVEL may correspond to 3~8 bits. In this case, theLL_INJECTION_LEVEL may be a field for identifying the injection level ofthe lower layer (enhanced layer). In this case, the LL_INJECTION_LEVELmay correspond to the injection level information.

In this case, the LL_INJECTION_LEVEL may be defined from the secondlayer (j>0) when the number of layers is two or more.

The fields such as PLP_ID(i,j), PLP_GROUP_ID, PLP_TYPE,PLP_PAYLOAD_TYPE, PLP_COD, PLP_MOD, PLP_SSD, PLP_FEC_TYPE,PLP_NUM_BLOCKS_MAX, IN_BAND_A_FLAG, IN_BAND_B_FLAG, PLP_MODE,STATIC_PADDING_FLAG, etc. may correspond to parameters which are definedfor each layer, and may be defined inside of the NUM_LAYER loop.

In this case, the PLP_ID(i,j) may correspond to the PLP identificationinformation and the layer identification information. For example, the‘i’ of the PLP_ID(i,j) may correspond to the PLP identificationinformation and the ‘j’ of the PLP_ID(i,j) may correspond to the layeridentification information.

In accordance with embodiments, the PLP identification information andthe layer identification information may be included in the preamble asfields different from each other.

Moreover, the time interleaver information such as the TIME_IL_LENGTHand TIME_IL_TYPE, etc., the FRAME_INTERVAL which is related to the PLPsize and fields such as FF_FLAG, FIRST_RF_IDX, FIRST_FRAME_IDX,RESERVED_1, STATIC_FLAG, etc. may be defined outside of the NUM_LAYERloop and inside of the NUM_PLP loop.

In particular, the PLP_TYPE corresponds to type information of thephysical layer pipes and may correspond to 1 bit for identifying oneamong two types, type 1 and type 2. The PLP_TYPE is included in thepreamble without checking a condition of a conditional statementcorresponding to the layer identification information (j) in the abovepseudo code, but the PLP_TYPE may be selectively signaled (transferredonly for the core layer) based on a result (if(j=0)) of comparing thelayer identification information (j) with a predetermined value (0).

The PLP_TYPE is defined in the NUM_LAYER loop in the above pseudo code,but the PLP_TYPE may be defined outside of the NUM_LAYER loop and insideof the NUM_PLP loop.

In the above pseudo code, the PLP_START corresponds to a start positionof the corresponding physical layer pipe. In this case, the PLP_STARTmay identify the start position using cell addressing scheme. In thiscase, the PLP_START may be an index corresponding to a first data cellof the corresponding PLP.

In particular, the PLP_START may be signaled for every physical layerpipe and may be used for identifying services using themultiple-physical layer pipes together with a field for signaling thesize of the PLP.

The PLP_SIZE in the above pseudo code corresponds to size information ofthe physical layer pipes. In this case, the PLP_SIZE may be identical tothe number of data cells assigned to the corresponding physical layerpipe.

That is, the PLP_TYPE may be signaled based on the layer identificationinformation and the PLP_SIZE and the PLP_START may be signaled for everyphysical layer pipe without considering the layer identificationinformation.

Channel bonding (CB) enables the bundling of multiple RF channels toprovide enhanced spectrum flexibility for broadcasting. CB spreads thedata of a single service (PLP) across two classical RF channels. Channelbonding enables increased peak service data rate beyond that offered bya single RF channel. The RF channels do not necessarily need to beadjacent to each other. Thus it is possible to receive channels from thesame (e.g. UHF-UHF) and different bands (e.g. VHF-UHF).

Another advantage by channel bonding is a potential increased frequencydiversity by extending frequency interleaving across more than one RFchannel (inter-RF frequency interleaving). This can be translated into acoverage gain for the reception of all the services transmitted into thetwo RF channels as well as an increased robustness against potentialinterferences in each one. A uniform distribution of the encoded dataacross two RF channels might allow the recovery of data even when one ofthe RF channels is corrupted as soon as a proper code rate is selected.

The increased robustness against interferences can also benefitfrequency planning by means of tighter frequency reuse patterns wherebymore RF channels can be used per transmitter station.

FIG. 20 is a block diagram showing a channel bonding transmitter.

Referring to FIG. 20 , the implementation of channel bonding shares mostof the blocks of the broadcast signal transmitter (the apparatus fortransmitting broadcast signal) using signal RF channel.

At the transmitter, the data of a high-capacity stream is divided intotwo sub-streams that are independently modulated and transmitted overtwo different RF channels.

FIG. 21 is a block diagram showing a channel bonding receiver.

Referring to FIG. 21 , two tuners are required to simultaneouslydemodulate the data of the two RF channels.

Two BICM decoding chains are also required. The demodulated streams arere-combined to generate the original single data stream.

The cell exchanger and cell re-exchanger of FIG. 20 and FIG. 21 may bebypassed with plain channel bonding and active with SNR averagingchannel bonding.

The plain channel bonding enables the transmission of services thatexceed single RF channel throughput as a basic mode.

The SNR averaging channel bonding exploits inter-RF frequencyinterleaving across the two RF channels, improving transmissionrobustness as a second operation mode. The cell exchanger is employed toensure an even distribution of the data across two RF channels.

FIG. 22 is a block diagram showing a broadcast signal transmitter withan input formatting block for BB header insertion.

Previous to the stream partitioner, transmitted data shall pass throughan input formatting block, where the baseband header (BB header) isinserted. The BB header contains a specific ID for the correctreordering of the packets at receiver side. Once data have beenpartitioned in BB packets, they are FEC encoded, modulated andtransmitted independently on different RF channels.

FIG. 23 is a block diagram showing a broadcast signal receiver with ablock for BB header removal.

The BB packets are assigned to the two modulation chains of the RFchannel proportionally to their rates so that the memory size of thestream combiner circuit at the receiver is not excessive.

BB header removal followed by stream combining is performed at thereceiver.

The cell exchanger of FIG. 20 distributes the odd and even cells of eachFEC codeword in each RF channel, respectively. The reverse operationtakes place at the receiver to recover data.

FIG. 24 is a diagram for explaining an operation of the cell exchanger.

Referring to FIG. 24 , the cell exchanger enables uniform distributionof encoded data across the two RF channels.

FIG. 25 is a diagram for mathematically expressing the output of thecell exchanger.

In FIG. 25 , s_(i,1) and s_(i,2) indicates the input cells of the cellexchanger and g_(i,1) and g_(i,2) indicates the output cells.

If the two RF channels are allocated in the same frequency band, SNRaveraging CB may be the optimum mode to be used. This mode imposes thePLP rates of both streams to be the same since the cell exchangerrequires the same cell rate in each transmitter branch. This way, it ispossible to double peak service data rate and obtain an improved RFperformance.

FIG. 26 is a block diagram showing an apparatus for transmittingbroadcast signal using SNR averaging CB and same band allocation.

Referring to FIG. 26 , the stream partitioner and the cell exchanger areused.

The block denoted as TI in FIG. 26 is a time interleaver, and may be thesame as the time interleaver 350 of FIG. 3 . The block denoted as Framerin FIG. 26 is a frame builder, and may be the same as the frame builder370 of FIG. 3 .

Moreover, the BICM of FIG. 26 may be the same as the BICM unit 310 or320 of FIG. 3 . The OFDM transmitter (OFDM generation) of FIG. 26 may bethe same as the OFDM transmitter 113 of FIG. 1 .

The block denoted as Fl in FIG. 26 is a frequency interleaver and mayperform interleaving corresponding to a frequency domain.

The block denoted as PP is a pilot pattern insertion unit and mayperform the pilot pattern insertion.

FIG. 27 is a block diagram showing an apparatus for receiving broadcastsignal using SNR averaging CB and same band allocation.

Referring to FIG. 27 , the cell re-exchanger and the stream combiner areused.

The block denoted as TI⁻¹ of FIG. 27 is a time deinterleaver and may bethe same as the time deinterleaver 510 of FIG. 8 . The block denoted asFramer⁻¹ may be a block configured to perform a reverse operation of theframe builder.

Moreover, the block denoted as BICM⁻¹ of FIG. 27 may be the same as theBICM decoder 520 or 540 of FIG. 8 . The OFDM receiver (OFDM generation)of FIG. 27 may be the same as the OFDM receiver 133 of FIG. 1 .

The block denoted as FI⁻¹ is a frequency deinterleaver and may performdeinterleaving corresponding to the frequency domain.

The channel estimation unit (Channel Estimation) may perform channelestimation using received signals. In this case, the pilot patterns maybe used for the channel estimation.

When the RF channels are allocated on different frequency bands,receivers must implement two different types of antenna. The use of SNRaveraging is less attractive. Instead, plain CB may be used in this caseand also in connection to SHVC (Scalable High efficiency Video Coding).The plain CB with SHVC would make possible to transmit a low data ratelayer (SHVC base layer) in one RF channel and a SHVC enhanced layer inthe other RF channel. This use case is advantageous for the jointdelivery of services for mobile and fixed reception. For example, amobile device implementing an embedded UHF antenna might be able todemodulate the lower data rate SHVC base layer. Fixed receivers with aUHF+VHF antenna might be able to receive a high quality service by meansof combining the base layer with the enhanced layer, the latter onetransmitted in the VHF channel.

FIG. 28 is a block diagram showing an apparatus for transmittingbroadcast signal using plain CB and different bands allocation.

Referring to FIG. 28 , each BICM chain modulates each different SHVClayer.

The operations of the blocks of FIG. 28 have been explained through FIG.26 .

FIG. 29 is a block diagram showing a mobile receiver using plain CB anddifferent bands allocation.

Referring to FIG. 29 , the mobile receiver only acquires the SHVC baselayer signal (SHVC BL).

FIG. 30 is a block diagram showing a fixed receiver using plain CB anddifferent bands allocation.

Referring to FIG. 30 , the fixed receiver recovers both SHVC layers(SHVC BL, SHVC EL).

The operations of the blocks of FIGS. 29 and 30 have been explainedthrough FIG. 27 .

The main purpose of layered division multiplexing (LDM) is thesimultaneous provision of fixed and mobile services sharing the sametime-frequency resources. The combination (joint implementation) of LDMand CB leads to the following use cases:

-   Plain CB for the LDM Enhanced Layer

In this use case, CB is applied only to the LDM fixed service layer. Thepeak data rate of the service can be doubled although no frequencydiversity gain is achieved. The LDM mobile layer would not implement CB,which does not increase mobile receiver complexity.

-   LDM with CB SNR averaging

In this use case, the mobile and fixed service data rates can be doubledbecause of the combination of 2 RF channels. SNR averaging can exploitinter-RF frequency diversity to enhance the transmission robustness.From an implementation point of view, the use of the cell-exchangerimposes that the same LDM transmission mode is used in the two RFchannels.

In plain CB for the LDM Enhanced Layer, the LDM core layer does notbenefit from an increased peak service data rate. However, this wouldnot force the implementation of two tuners at mobile receivers, thus,relaxing the mobile receiver complexity. On the other hand, the EL wouldbenefit from the Plain CB advantages.

The plain CB may be the only admissible CB mode due to the impossibilityof mixing two independent core layer (CL) streams at the cell exchanger.

FIG. 31 is a block diagram showing an apparatus for transmittingbroadcast signal according to an embodiment of the present invention.

Referring to FIG. 31 , the apparatus for transmitting broadcast signalaccording to an embodiment of the present invention includes an enhancedlayer stream partitioner 3110, the first core layer BICM unit 3121, thesecond core layer BICM unit 3124, the first and second enhanced layerBICM units 3122 and 3123, the first and second injection levelcontrollers 3131 and 3132, combiners 3141 and 3142, power normalizers3151 and 3152, time interleavers 3161 and 3162, frame builders 3171 and3172, frequency interleavers 3181 and 3182, pilot pattern insertionunits 3191 and 3192, and OFDM transmitters 3115 and 3116.

The enhanced layer stream partitioner 3110 generates the first enhancedlayer partitioned signal (EL Input Stream 1) and the second enhancedlayer partitioned signal (EL Input Stream 2) by partitioning an enhancedlayer stream.

Each of the first and the second core layer BICM units 3121, 3124 andthe first and second enhanced layer BICM units 3122 and 3123 may be oneof the BICM units 310 and 320 of FIG. 3 .

Each of the injection level controllers 3131 and 3132 may be theinjection level controller 330 of FIG. 3 .

The combiner 3141 generates the first multiplexed signal correspondingto the first enhanced layer partitioned signal (EL input stream 1). Thecombiner 3142 generates the second multiplexed signal corresponding tothe second enhanced layer partitioned signal (EL input stream 2). Eachof the combiners 3141 and 3142 may be the combiner 340 of FIG. 3 . Thecombiner 3141 may generate the first multiplexed signal by combining thefirst core layer signal and the first enhanced layer partitioned signalat power levels different from each other. The combiner 3142 maygenerate the second multiplexed signal by combining the second corelayer signal and the second enhanced layer partitioned signal at powerlevels different from each other.

The power normalizer 3151 reduces the power of the first multiplexedsignal to power level corresponding to the first core layer signal. Thepower normalizer 3152 reduces the power of the second multiplexed signalto power level corresponding to the second core layer signal. Each ofthe power normalizers 3151 and 3152 may be the power normalizer 345 ofFIG. 3 .

The time interleaver 3161 generates the first time-interleaved signalcorresponding to the first enhanced layer partitioned signal. The timeinterleaver 3162 generates the second time-interleaved signalcorresponding to the second enhanced layer partitioned signal. Each ofthe time interleavers 3161 and 3162 may be the time interleaver 350 ofFIG. 3 .

Each of the frame builders 3171 and 3172 may be the frame builder 370 ofFIG. 3 .

The operations of the frequency interleavers 3181, 3182 and pilotpattern insertion units 3191 and 3192 have already been explained.

The OFDM transmitter 3115 transmits the signal corresponding to thefirst time-interleaved signal using the OFDM communication scheme. TheOFDM transmitter 3116 transmits the signal corresponding to the secondtime interleaved signal using the OFDM communication scheme. Each of theOFDM transmitters 3115 and 3116 may be the OFDM transmitter 113 of FIG.1 .

In the exemplary embodiment of FIG. 31 , the first core layer signal andthe second core layer signal may be independent from each other.

The inputs of the apparatus of FIG. 31 are two independent core layer(CL) streams and one enhanced layer (EL) stream that is divided into twoEL sub-streams. Each EL sub-stream (each enhanced layer partitionedsignal) is LDM-aggregated to one of the CL streams forming two LDMsignals which are transmitted in different RF channels. Thus, the streampartitioner is only applied to the EL stream.

FIG. 32 is a block diagram showing a mobile broadcast signal receiversaccording to an embodiment of the present invention.

Referring to FIG. 32 , the mobile broadcast signal receivers accordingto an embodiment of the present invention are single-tuner receivers,respectively.

Each of the mobile broadcast signal receivers of FIG. 32 receives one CLstream depending on the RF channel to which they are tuned.

FIG. 33 is a block diagram showing a fixed broadcast signal receiveraccording to an embodiment of the present invention.

Referring to FIG. 33 , the fixed broadcast signal receiver according toan embodiment of the present invention includes OFDM receivers 3311,3312, channel estimation units 3321, 3322, time deinterleavers 3331,3332, core layer BICM decoders 3351, 3352, enhanced layer BICM decoders3361, 3362 and an enhanced layer stream combiner 3370.

The OFDM receiver 3311 receives the first receiving signal. The OFDMreceiver 3312 receives the second receiving signal. Each of the OFDMreceivers 3311 and 3312 may be the OFDM receiver 133 of FIG. 1 .

The time deinterleaver 3331 generates the first time deinterleavingsignal by applying time deinterleaving to the first receiving signal.The time deinterleaver 3332 generates the second time deinterleavingsignal by applying time deinterleaving to the second receiving signal.Each of the time deinterleaver 3331 and 3332 may be the timedeinterleaver 510 of FIG. 8 .

The core layer BICM decoder 3351 restores the first core layer signal(CL Output Stream A) from the signal corresponding to the firstreceiving signal. The core layer BICM decoder 3352 restores the secondcore layer signal (CL Output Stream B) from the signal corresponding tothe second receiving signal. Each of the core layer BICM decoders 3351and 3352 may be the core layer BICM decoder 520 of FIG. 8 .

The enhanced layer BICM decoder 3361 restores the first enhanced layerpartitioned signal (EL Output Stream 1) based on cancellationcorresponding to the first core layer signal. The enhanced layer BICMdecoder 3362 restores the second enhanced layer partitioned signal (ELOutput Stream 2) based on cancellation corresponding to the second corelayer signal. Each of the enhanced layer BICM decoder 3361 and 3362 maybe the enhanced layer BICM decoder 540 of FIG. 8 .

The enhanced layer stream combiner 3370 generates the enhanced layerstream by combining the first enhanced layer partitioned signal (ELOutput Stream 1) and the second enhanced layer partitioned signal (ELOutput Stream 1).

In this case, the first core layer signal and the second core layersignal may be independent from each other.

The fixed broadcast signal receiver of FIG. 33 first recovers the twoindependent CL streams with two different tuners. Then, the LDMcancellation process takes place in order to obtain the two ELsub-streams, which are finally re-combined in the stream combiner.

In LDM with CB SNR averaging, the SNR averaging channel bonding isapplied for both LDM layers (the core layer and enhanced layer).Although the use of plain CB for both layers is also possible, theimplementation of SNR averaging CB is proper when the two RF channelsare in the same band in order to also exploit the frequency diversitygain.

FIG. 34 is a block diagram showing an apparatus for transmittingbroadcast signal according to another embodiment of the presentinvention.

Referring to FIG. 34 , the apparatus for transmitting broadcast signalaccording to another embodiment of the present invention includes a corelayer stream partitioner 3410, a cell exchanger 3420, an enhanced layerstream partitioner 3110, the first core layer BICM unit 3121, the secondcore layer BICM unit 3124, the first and second enhanced layer BICMunits 3122 and 3123, the first and second injection level controllers3131 and 3132, combiners 3141 and 3142, power normalizers 3151 and 3152,time interleavers 3161 and 3162, frame builders 3171 and 3172, frequencyinterleavers 3181 and 3182, pilot pattern insertion units 3191 and 3192,and OFDM transmitters 3115 and 3116.

The core layer stream partitioner 3410 generates the first core layersignal (CL Input Stream 1) and the second core layer signal (CL InputStream 2) by partitioning a core layer stream.

The enhanced layer stream partitioner 3110 generates the first enhancedlayer partitioned signal (EL Input Stream 1) and the second enhancedlayer partitioned signal (EL Input Stream 2) by partitioning theenhanced layer stream.

Each of the first and the second core layer BICM units 3121, 3124 andthe first and second enhanced layer BICM units 3122 and 3123 may be oneof the BICM units 310 and 320 of FIG. 3 .

Each of the injection level controllers 3131 and 3132 may be theinjection level controller 330 of FIG. 3 .

The combiner 3141 generates the first multiplexed signal correspondingto the first enhanced layer partitioned signal (EL input stream 1). Thecombiner 3142 generates the second multiplexed signal corresponding tothe second enhanced layer partitioned signal (EL input stream 2). Eachof the combiners 3141 and 3142 may be the combiner 340 of FIG. 3 . Thecombiner 3141 may generate the first multiplexed signal by combining thefirst core layer signal and the first enhanced layer partitioned signalat power levels different from each other. The combiner 3142 maygenerate the second multiplexed signal by combining the second corelayer signal and the second enhanced layer partitioned signal at powerlevels different from each other.

The power normalizer 3151 reduces the power of the first multiplexedsignal to power level corresponding to the first core layer signal. Thepower normalizer 3152 reduces the power of the second multiplexed signalto power level corresponding to the second core layer signal. Each ofthe power normalizers 3151 and 3152 may be the power normalizer 345 ofFIG. 3 .

The cell exchanger 3420 distributes odd and even cells from the outputsignals of the power normalizers 3151 and 3152.

The time interleaver 3161 generates the first time-interleaved signalcorresponding to the first enhanced layer partitioned signal. The timeinterleaver 3162 generates the second time-interleaved signalcorresponding to the second enhanced layer partitioned signal. Each ofthe time interleavers 3161 and 3162 may be the time interleaver 350 ofFIG. 3 .

Each of the frame builders 3171 and 3172 may be the frame builder 370 ofFIG. 3 .

The operations of the frequency interleavers 3181, 3182 and pilotpattern insertion units 3191 and 3192 have already been explained.

The OFDM transmitter 3115 transmits the signal corresponding to thefirst time-interleaved signal using the OFDM communication scheme. TheOFDM transmitter 3116 transmits the signal corresponding to the secondtime interleaved signal using the OFDM communication scheme. Each of theOFDM transmitters 3115 and 3116 may be the OFDM transmitter 113 of FIG.1 .

In this case, the OFDM transmitters 3115 and 3116 may use the samefrequency band.

In contrast to the embodiment of FIG. 31 , the CL sub-streams are nolonger independent but form part of a stream that is partitioned in theembodiment of FIG. 34 . In such case, two stream partitioners (one perlayer stream) are required. The cell exchanger 3420 is in charge ofuniform distribute the CL+EL cells.

FIG. 35 is a block diagram showing a mobile broadcast signal receiveraccording to another embodiment of the present invention.

Referring to FIG. 35 , the mobile broadcast signal receiver shouldimplement two tuners. The cell re-exchanger is used in order to get thecore layer stream.

FIG. 36 is a block diagram showing a fixed broadcast signal receiveraccording to another embodiment of the present invention.

Referring to FIG. 36 , the fixed broadcast signal receiver according toanother embodiment of the present invention includes OFDM receivers3311, 3312, channel estimation units 3321, 3322, time deinterleavers3331, 3332, a cell re-exchanger 3610, core layer BICM decoders 3351,3352, enhanced layer BICM decoders 3361, 3362, an enhanced layer streamcombiner 3370 and a core layer stream combiner 3620.

The OFDM receiver 3311 receives the first receiving signal. The OFDMreceiver 3312 receives the second receiving signal. Each of the OFDMreceivers 3311 and 3312 may be the OFDM receiver 133 of FIG. 1 .

The time deinterleaver 3331 generates the first time deinterleavingsignal by applying time deinterleaving to the first receiving signal.The time deinterleaver 3332 generates the second time deinterleavingsignal by applying time deinterleaving to the second receiving signal.Each of the time deinterleaver 3331 and 3332 may be the timedeinterleaver 510 of FIG. 8 .

The cell re-exchanger 3610 performs a cell re-exchange corresponding tooutput signals of the time deinterleavers 3331 and 3332.

The core layer BICM decoder 3351 restores the first core layer signal(CL Output Stream A) from the signal corresponding to the firstreceiving signal. The core layer BICM decoder 3352 restores the secondcore layer signal (CL Output Stream B) from the signal corresponding tothe second receiving signal. Each of the core layer BICM decoders 3351and 3352 may be the core layer BICM decoder 520 of FIG. 8 .

The enhanced layer BICM decoder 3361 restores the first enhanced layerpartitioned signal (EL Output Stream 1) based on cancellationcorresponding to the first core layer signal. The enhanced layer BICMdecoder 3362 restores the second enhanced layer partitioned signal (ELOutput Stream 2) based on cancellation corresponding to the second corelayer signal. Each of the enhanced layer BICM decoders 3361 and 3362 maybe the enhanced layer BICM decoder 540 of FIG. 8 .

The enhanced layer stream combiner 3370 generates the enhanced layerstream by combining the first enhanced layer partitioned signal (ELOutput Stream 1) and the second enhanced layer partitioned signal (ELOutput Stream 1).

The core layer stream combiner 3620 generates the core layer stream bycombining the first core layer signal (CL output Stream 1) and thesecond core layer signal (CL Output Stream 2).

In this case, the OFDM receivers 3311 and 3312 may use the samefrequency band.

The fixed broadcast signal receiver of FIG. 36 performs the LDMcancellation process twice for the enhanced layer recovery. Moreover,the fixed broadcast signal receiver of FIG. 36 includes a second streamcombiner for the enhanced layer in comparison with the mobile receiverof FIG. 35 .

FIG. 37 is an operation flowchart showing a method of transmittingbroadcast signal according to an embodiment of the present invention.

Referring to FIG. 37 , in the method of transmitting broadcast signalaccording to the embodiment of the present invention, the first enhancedlayer partitioned signal and the second enhanced layer partitionedsignal are generated by partitioning the enhanced layer stream at stepS3710.

Furthermore, in the method according to the embodiment of the presentinvention, the first multiplexed signal corresponding to the firstenhanced layer partitioned signal and the second multiplexed signalcorresponding to the second enhanced layer partitioned signal aregenerated at step S3720.

Furthermore, in the method according to the embodiment of the presentinvention, the powers of the first and second multiplexed signals arereduced to power levels corresponding to the first core layer signal andthe second core layer signal, respectively, at step S3730.

Furthermore, in the method according to the embodiment of the presentinvention, the first time interleaved signal corresponding to the firstenhanced layer partitioned signal and the second time interleaved signalcorresponding to the second enhanced layer partitioned signal aregenerated at step S3740.

Furthermore, in the method according to the embodiment of the presentinvention, the signals corresponding to the first time interleavedsignal and the second time interleaved signal are transmitted using anOFDM communication scheme at step S3750.

In this case, at step S3720, the first multiplexed signal may begenerated by combining the first core layer signal and the firstenhanced layer partitioned signal at different power levels, and thesecond multiplexed signal may be generated by combining the second corelayer signal and the second enhanced layer partitioned signal atdifferent power levels.

In this case, the first core layer signal and the second core layersignal may be independent from each other.

Although not explicitly shown in FIG. 37 , the method may furtherinclude the step of distributing odd and even cells from the outputsignals of the step S3730.

Although not explicitly shown in FIG. 37 , the method may furtherinclude the step of generating the first core layer signal and thesecond core layer signal by partitioning a core layer stream.

In this case, the step S3750 may use the same frequency band.

In channel bonding, data of a single PLP connection is spread over twoor more different RF channels. In this case, the channel bonding may beused for improving service data rates and may be used to exploit thefrequency diversity among multiple RF channels. A plurality of RFchannels used for channel bonding may be located at adjacent channelfrequencies or not necessarily adjacent to each other.

FIG. 38 is a block diagram showing one exemplarily embodiment of anapparatus for transmitting broadcast signal to which channel bonding isapplied.

Referring to FIG. 38 , the apparatus for transmitting broadcast signalincludes an input formatting unit 3810, a stream partitioner 3820, BICMunits 3831 and 3832, framing/interleaving units 3841 and 3842, andwaveform generators 3851 and 3852. The apparatus for transmittingbroadcast signal may further include a cell exchanger 3860 when SNRaveraging channel bonding is applied.

Although only the structure of the transmitting apparatus is illustratedin FIG. 38 , a receiving apparatus corresponding to the transmittingapparatus of FIG. 38 may also be clearly explained from the structureillustrated in FIG. 38 .

The input formatting unit 3810 generates baseband packets correspondingto a plurality of packet types using data corresponding to a singlephysical layer pipe.

The baseband packet generation and the BB header insertion operation ofthe input formatting unit 3810 have already been described above. Inthis case, the extension field of the baseband packet header may be usedas a counter for correctly reordering baseband packets transmittedthrough different RF channels at the receiver.

In this case, the packet types may be one-to-one mapped to RF channelsto be channel bonded. That is, the packet types may be fordistinguishing packets transmitted through different RF channels. Inthis case, a baseband packet corresponding to a specific packet type mayhave the same length as a baseband packet corresponding to anotherpacket type or may have a different length from the baseband packetcorresponding to another packet type. For example, the packet type maybe distinguished (identified) by a combination of an RF channelidentifier L1D_rf_id and a physical layer pipe identifier L1D_plp_id.

In this case, the input formatting unit 3810 may generate basebandpackets corresponding to one of the plurality of packet types using abaseband packet length corresponding to BICM parameters for one of theRF channels RF Channel 1 and RF Channel 2.

In this case, the BICM parameters may include at least one of a FEC typeparameter, a code rate parameter and/or a modulation parametercorresponding to the one of the RF channels.

In this case, the FEC type parameter L1D_plp_fec_type may be a 4-bitparameter and may indicate a forward error correction method.

For example, L1D_plp_fec_type which is “0000” may indicate that BCH and16200 LDPC are used as the forward error correction method,L1D_plp_fec_type which is “0001” may indicate that BCH and 64800 LDPCare used as the forward error correction method, L1D_plp_fec_type whichis “0010” may indicate that CRC and 16200 LDPC are used as the forwarderror correction method, L1D_plp_fec_type which is “0011” may indicatethat CRC and 64800 LDPC are used as the forward error correction method,L1D_plp_fec_type which is “0100” may indicate that only 16200 LDPC isused as the forward error correction method, and L1D_plp_fec_type whichis “0101” may indicate that only 64800 LDPC is used for the forwarderror correction method.

In this case, BCH indicates Bose, Chaudhuri, Hocquenghem, CRC indicatesCyclic Redundancy Check, and LDPC indicates Low-Density Parity Check.

In this case, the code rate parameter L1D_plp_code may be a 4-bitparameter and may indicate a code rate.

For example, L1D_plp_code which is “0000” may indicate that the coderate is 2/15, L1D_plp_code which is “0001” may indicate that the coderate is 3/15, L1D_plp_code which is “0010” may indicate that the coderate is 4/15, L1D_plp_code which is “0011” may indicate that the coderate is 5/15, L1D_plp_code which is “0100” may indicate that the coderate is 6/15, L1D_plp_code which is “0101” may indicate that the coderate is 7/15, L1D_plp_code which is “0110” may indicate that the coderate is 8/15, L1D_plp_code which is “0111” may indicate that the coderate is 9/15, L1D_plp_code which is “1000” may indicate that the coderate is 10/15, L1D_plp_code which is “1001” may indicate that the coderate is 11/15, L1D_plp_code which is “1010” may indicate that the coderate is 12/15, and L1D_plp_code which is “1011” may indicate that thecode rate is 13/15.

In this case, the modulation parameter L1D_plp_mode may be a 4-bitparameter and may indicate a modulation scheme.

For example, L1D_plp_mode which is “0000” may indicate QPSK,L1D_plp_mode which is “0001” may indicate 16QAM-NUC, L1D_plp_mode whichis “0010” may indicate 64QAM-NUC, L1D_plp_mode which is “0011” mayindicate 256QAM-NUC, L1D_plp_mode which is “0100” may indicate1024QAM-NUC, and L1D_plp_mode which is “0101” may indicate 4096QAM-NUC.In this case, QPSK indicates Quadrature Phase Shift Keying, QAMindicates Quadrature Amplitude Modulation, and NUC indicates Non-UniformConstellation.

The stream partitioner 3820 partitions the baseband packets into aplurality of partitioned streams corresponding to the plurality ofpacket types. The stream partitioner 3820 has already been describedabove with reference to FIGS. 26 or 28 . In this case, the partitionedstreams may be identified by a combination of the RF channel identifierL1D_rf_id corresponding to one of the RF channels RF Channel 1 and RFChannel 2, and the physical layer pipe identifier L1D_plp_idcorresponding to the single physical layer pipe.

In this case, the input formatting unit 3810 may decide the number(N_(BBpacket)) of consecutive baseband packets for each of the packettypes, and may allocate consecutively as many baseband packets as thenumber of consecutive baseband packets corresponding to each of thepacket types.

In this case, the stream partitioner 3820 may perform partitioning usingthe number of consecutive baseband packets corresponding to each of thepacket types.

At the output of the stream partitioner 3820, the baseband packets ofthe bonded PLP for each of the two partitioned streams are FEC encoded,interleaved and modulated individually and transmitted on different RFchannels.

In particular, for plain channel bonding, the two transmission chainsoperates without any interaction after the stream partitioner 3820. Inthis case, each RF channel may use different parameter settings such asbandwidth, modulation, coding, FFT, guard interval length, and so on.Each RF channel is effectively handled as a standalone signal.

When bonded RF channels are configured with different BICM parametersfor a channel bonded PLP, the baseband packets for that channel bondedPLP may have a different length on each of those bonded RF channels.When the baseband packet is generated for the channel bonded PLP, theinput formatting unit 3810 shall use the baseband packet lengthcorresponding to the channel bonded PLP’s BICM parameters for the RFchannel over which that baseband packet will be processed andtransmitted.

In this case, the stream partitioner 3820 may allocate no more than 5consecutive baseband packets to the same RF channel.

In this case, the baseband packets may include baseband packetscorresponding to two or more different baseband packet lengths.

Each of the BICM units 3831 and 3832 performs error correction encoding,interleaving and modulation corresponding to each of the plurality ofpartitioned streams. The BICM units 3831 and 3832 have already beenexplained above with reference to FIGS. 26 or 28 .

In this case, the BICM units 3831 and 3832 may perform the errorcorrection encoding, the interleaving and the modulation for each of theplurality of partitioned streams individually.

The cell exchanger 3860 exchanges cells corresponding to two RF channelsRF Channel 1 and RF Channel 2 shown in FIG. 38 . The cell exchanger 3860has been explained above with reference to FIGS. 24, 26 or 28 .

Each of the framing/interleaving units 3841 and 3842 performs framingand interleaving operation corresponding to each of the two RF channelsRF Channel 1 and RF Channel 2. In this case, each of theframing/interleaving units 3841 and 3842 may include TI block, Framerblock and FI block explained through FIG. 26 or FIG. 28 .

Each of the waveform generators 3851 and 3852 generates RF transmissionsignal corresponding to each of the plurality of partitioned streams. Inthis case, each of the waveform generators 3851 and 3852 may include thePP block and the OFDM generation explained thorough FIG. 26 or FIG. 28 .

FIG. 39 is a block diagram showing a case in which the input formattingunit of FIG. 38 generates baseband packets for two PLPs.

Referring to FIG. 39 , the input formatting unit 3810 of FIG. 38generates baseband packets corresponding to two physical layer pipesPLP0 and PLP1.

K_(payload) in FIG. 39 indicates the length of the baseband packet. Inthis case, FEC frame may be generated by adding parity bits to the bitstring corresponding to K_(payload).

K_(payload) of each physical layer pipe may be decided by a FEC typeparameter L1D_plp_fec_type and a code rate parameter L1D_plp_cod amongthe BICM parameters In general, each combination of the FEC typeparameter L1D_plp_fec_type and the code rate parameter L1D_plp_codcreates different K_(payload).

However, when CRC is used for outer code, K_(payload) may be the samefor different combination of the FEC type parameter L1D_plp_fec_type andthe code rate parameter L1D_plp_cod. That is, different combination ofthe FEC type parameter L1D_plp_fec_type and the code rate parameterL1D_plp_cod may result in different baseband packet length in general,but there may be a case in which K_(payload) is the same. For example,K_(payload) is 8608 for the code length of 64800 and the code rate of2/15, and K_(payload) is 8608 (K_(payload) is the same) for the codelength of 16200 and the code rate of 8/15 when CRC is used for outercode. For example, K_(payload) is 12928 for the code length of 64800 andthe code rate of 3/15, and K_(payload) is 12928 (K_(payload) is thesame) for the code length of 16200 and the code rate of 12/15 when CRCis used for outer code.

FIG. 40 is a block diagram showing a case in which the input formattingunit of FIG. 38 channel-bonds two RF channels.

Referring to FIG. 40 , the input formatting unit 4010 generates basebandpackets corresponding to a plurality of packet types, and the streampartitioner 4020 partitions the baseband packets for each packet type.In this case, the packet type may indicate the RF channel through whichthe corresponding packets are to be transmitted. For example, thebaseband packet lengths may be different for different packet types, andthe same baseband packet length may be used for different packet types.

In this case, the baseband packets which are generated by the inputformatting unit 4010 may include baseband packets with differentlengths. For example, the baseband packet for the second RF channel andthe baseband packet for the first RF channel may have the same length.

In an example of FIG. 40 , the input formatting unit 4010 may correspondto the input formatting unit 3810 in FIG. 38 , and the streampartitioner 4020 may correspond to the stream partitioner 3820 of FIG.38 .

When channel bonding is used, the input formatting unit 4010 may use amodulation parameter L1D_plp_mod as well as a FEC type parameterL1D_plp_fec_type and a code rate parameter L1D_plp_cod. In this case,the modulation parameter L1D_plp_mod may be used in order to keeptransmission cell rate for each RF channel the same.

In this case, N_(BBpacket) may indicate the number of consecutivebaseband packets for each RF channel. That is, N_(BBpacket) for each RFchannel may be defined as the number of consecutive baseband packets foreach RF channel in output stream of the input formatting unit 4010. Inan example of FIG. 40 , N_(BBpacket) for the RF channel RF0 may be 2 andN_(BBpacket) for the RF channel RF1 may be 1. In this case, the ratio ofN_(BBpacket) for the RF channel RF0 and N_(BBpacket) for the RF channelRF1 may be decided by the ratio of code length X modulation order foreach RF channel.

For example, the ratio of N_(BBpacket) of the RF channel RF0 andN_(BBpacket) of the RF channel RF1 may be 2:1 when the code length is64800 and the modulation order is 2 (QPSK) for the RF channel RF0 andthe code length is 16200 and the modulation order is 4 (16QAM) for theRF channel RF1. That is, N_(BBpacket) for RF0 : N_(BBpacket) for RF1 =64800 × 2 : 16200 × 4 = 2 : 1.

As shown in the example of FIG. 40 , when N_(BBpacket) of the RF channelRF0 is decided to 2 and N_(BBpacket) of the RF channel RF1 is decided to1, the input formatting unit 4010 illustrated in FIG. 40 assigns twobaseband packets for the RF channel RF0 and assigns one baseband packetfor the RF channel RF1, and then assigns two baseband packets for the RFchannel RF0 and assigns one baseband packet for the RF channel RF1, andthese operations are repeated.

The stream partitioner 4020 may extract the baseband packets only foreach channel from the output stream of the input formatting unit 4010and assign the extracted baseband packets properly to the BICM unit foreach RF channel if the stream partitioner 4020 knows the ratio (2:1) ofN_(BBpacket)s for RF channels.

In FIG. 40 , the cell rates of the two RF channels are equally adjustedbut N_(BBpacket) corresponding to each RF channel may be set regardlessof the cell rate when plain channel bonding is applied.

FIG. 41 is an operation flowchart showing a method of transmittingbroadcast signal using channel bonding according to an embodiment of thepresent invention.

Referring to FIG. 41 , the method of transmitting broadcast signal usingchannel bonding according to an embodiment of the present inventiongenerates broadband packets corresponding to a plurality of packet typesusing data corresponding to a physical layer pipe (S4110).

In this case, the packet types may be one-to-one mapped to RF channelsto be channel bonded.

In this case, the step S4110 may generate baseband packets correspondingto one of the plurality of packet types using a baseband packet lengthcorresponding to BICM parameters for one of the RF channels.

In this case, the BICM parameters may include at least one of a FEC typeparameter, a code rate parameter and/or a modulation parametercorresponding to the one of the RF channels.

In this case, the step S4110 may decide the number (N_(BBpacket)) ofconsecutive baseband packets for each of the packet types, and allocateconsecutively as many baseband packets as the number of consecutivebaseband packets corresponding to each of the packet types.

In this case, the baseband packets may include baseband packetscorresponding to two or more different baseband packet lengths.

Further, the method of transmitting broadcast signal partitions thebaseband packet into a plurality of partitioned streams corresponding tothe plurality of packet types (S4120).

In this case, the step S4120 may be performed using the number ofconsecutive baseband packets corresponding to each of the packet types.

In this case, the step S4120 may allocate no more than 5 consecutivebaseband packets to the same RF channel.

In this case, the partitioned streams may be identified corresponding toa combination of a RF channel identifier (L1D_rf_id) corresponding toone of the RF channels and a physical layer pipe identifier (L1D_plp_id)corresponding the physical layer pipe.

Further, the method of transmitting broadcast signal performs errorcorrection encoding, interleaving and modulation corresponding to eachof the plurality of partitioned streams (S4130).

In this case, the step S4130 may be performed individually for each ofthe plurality of partitioned streams.

Further, the method of transmitting broadcast signal generates RFtransmission signals corresponding to the plurality of partitionedstreams, respectively (S4140).

FIG. 42 is a block diagram showing a broadcast signal transmissionsystem according to an embodiment of the present invention.

Referring to FIG. 42 , a broadcast signal transmission system accordingto an embodiment of the present invention includes a broadcast gatewayapparatus 4210 and multiple transmitters 4221, 4222 and 4223.

The broadcast gateway apparatus 4210 transmits a broadcast transmissionpacket for a broadcast service to one or more of the multipletransmitters 4221, 4222 and 4223. Here, the broadcast transmissionpacket may be transmitted via a Studio-to-Transmitter Link (STL). Here,the broadcast transmission packet may be a packet based on aStudio-to-Transmitter Link Transport (tunneling) Protocol (STLTP).

The Studio-to-Transmitter Link (STL) may be a datatransmission/reception link between the broadcast gateway apparatus 4210and the transmitters 4221, 4222 and 4223 in the broadcast transmissionsystem, and may be a fiber, satellite, or microwave link. Here, the STLmay be a wired or wireless link, and may be a link through which data istransmitted and received using a packet-based protocol, such asRTP/UDP/IP or the like.

The transmitters 4221, 4222 and 4223 generate broadcast signals to beprovided to receivers using the broadcast transmission packetstransmitted from the broadcast gateway apparatus 4210 and transmit thegenerated broadcast signals to the receivers over a broadcast network.Here, the transmitters 4221, 4222 and 4223 may be high-powertransmitters, or may be low-power transmitters, such as gap fillers orthe like.

Here, when the multiple transmitters 4221, 4222 and 4223 are high-powertransmitters, broadcast companies may use a dedicated network for areliable STL. Here, when the multiple transmitters 4221, 4222 and 4223are low-power transmitters for coverage extension, broadcast companiesmay use a public network for the transmission of broadcast transmissionpackets, rather than using a dedicated network.

Here, when the STL between the broadcast gateway apparatus 4210 and themultiple transmitters 4221, 4222 and 4223 is based on a public network,there is an advantage in that costs may be reduced compared to the casein which a dedicated network is used, but reliability may be reduced.

Accordingly, what is required a method for guaranteeing reliability whenthe STL between the broadcast gateway apparatus 4210 and the multipletransmitters 4221, 4222 and 4223 uses a public network.

For example, when a public network is used, redundancy may be providedby transmitting a plurality of identical broadcast transmission packets,or an Error Correction Code (ECC) may be applied to broadcasttransmission packets.

For example, when the transmitter 4221 is a main high-power transmitter,a dedicated network may be used in order to transmit a broadcasttransmission packet from the broadcast gateway apparatus 4210 to thetransmitter 4221. Here, the broadcast transmission packet may be amulticast IP packet.

For example, when the transmitter 4222 is a less important low-powertransmitter or gap filler, a public network may be used in order totransmit a broadcast transmission packet from the broadcast gatewayapparatus 4210 to the transmitter 4222. Here, the broadcast transmissionpacket may be a unicast IP packet.

Here, in the case of transmission of a unicast IP packet over a publicnetwork, in order to improve reliability, redundancy may be provided,and an error correction code (ECC) may be applied.

Here, the broadcast transmission packet may correspond to an outerpacket. That is, first, an inner packet may be generated byencapsulating a baseband packet, a preamble, and a timing and managementpacket, and an outer packet may be generated using the inner packet.Here, the outer packet may be the broadcast transmission packet.

That is, the inner packet may be tunneled by the outer packet, the outerpacket may be a tunneling packet, and the inner packet may be a tunneledpacket.

Here, the inner packet includes a baseband packet, a preamble packet,and a timing and management packet, and may correspond to the innerlayer of a tunneling system. Here, the outer packet may correspond tothe outer layer of the tunneling system. Here, the inner packet may beencapsulated through the outer packet.

Here, the tunneling system may correspond to a process by which a groupof parallel and independent packet streams corresponding to the innerpacket are carried within a single packet stream corresponding to theouter packet.

Here, one or more inner packets may constitute an inner tunneled packetstream, and one or more outer packets may constitute an outer tunneldata stream.

When channel bonding is used, the broadcast gateway apparatus 4210 ofFIG. 42 may include an input formatting unit and a stream partitionerfor the channel bonding. In this case, the input formatting unit maygenerate baseband packets corresponding to the channel bonding. In thiscase, the stream partitioner may allocate the baseband packets (ofchannel-bonded PLP(s)) to two or more RF channels for the channelbonding.

The broadcast gateway apparatus 4210 may include a stream partitionerfor channel bonding so that each of the transmitters 4221, 4222 and 4223can generate an appropriate broadcast signal for the channel bonding andtransmit the generated broadcast signal to receivers.

FIG. 43 is a block diagram showing one exemplarily embodiment of abroadcast signal transmission system when plain channel bonding forcolocated transmitters is applied.

Referring to FIG. 43 , two outer tunnel data streams (STL A, STL B) forchannel bonding are transmitted from the broadcast gateway apparatus4310 to the transmitter 4320.

In this case, the transmitter 4320 may be a colocated transmitter. Inthis case, the colocated transmitter may include multiple RFtransmission modules in a single transmitter to transmit channel-bondedRF transmission signals. That is, the colocated transmitter may includemultiple physical layer chains.

For example, when the plain channel bonding is used, enabled byL1D_plp_channel_bonding_format = 00 in L1-Detail of the preamble, theouter tunnel data streams of a bonded PLP may use two differentRTP/UDP/IP multicast (or unicast) protocols in order to be processedthrough two RF channels.

In this case, if there is a PLP that is not channel-bonded amongmultiple PLPs being serviced, a broadcast gateway apparatus 4310 mayneed to configure which RTP/UDP/IP multicast (or unicast) protocol thatPLP be delivered without performing the stream partitioning.

In the example of FIG. 43 , the single transmitter 4320 may receive twoouter tunnel data packet streams.

The broadcast gateway apparatus 4310 may include the input formattingunit 4311 and the stream partitioner 4313.

The input formatting unit 4311 generates baseband packets correspondingto the channel bonding.

The stream partitioner 4313 allocates the baseband packets to two ormore RF channels for the channel bonding. In this case, the basebandpackets may be for generating the outer tunnel data stream. In thiscase, the outer tunnel data stream may be generated in different waysaccording to multiple operation modes for the channel bonding.

The transmitter 4320 may include STL receivers 4321 and 4322, BICM units4323 and 4324, framing/interleaving units 4325 and 4326 and waveformgenerators 4327 and 4328.

In this case, each of the STL receivers 4321 and 4322 receives the outertunnel data stream which are transmitted through the Studio toTransmitter Link (STL). In this case, the outer tunnel data stream maycorrespond to the channel bonding.

The STL receivers 4321 and 4322 may extract the outer packet from thereceived outer tunnel data stream, and extract the corresponding innerpacket. For this, the STL receivers 4321 and 4322 may extract the RTPpacket header, etc.

The structure and operation of the BICM units 4323 and 4324, theframing/interleaving units 4325 and 4326, and the waveform generators4327 and 4328 have been described above.

FIG. 44 is a block diagram showing one exemplarily embodiment of abroadcast signal transmission system when plain channel bonding fornon-colocated transmitters is applied.

Referring to FIG. 44 , each of the transmitters 4420 and 4430 receivesone outer tunnel data stream from the broadcast gateway apparatus 4410.In this case, the transmitter 4420 may receive the outer tunnel datastream (STL A) for the RF channel A, and the transmitter 4430 mayreceive the outer tunnel data stream (STL B) for the RF channel B.

In this case, the non-colocated transmitter may include only one RFtransmission module in a single transmitter to transmit one RFtransmission signal. That is, the non-colocated transmitter may includeone physical layer chain.

The broadcast gateway apparatus 4410 may include the input formattingunit 4411 and the stream partitioner 4413.

The operation of the broadcast gateway apparatus 4410 and the streampartitioner 4413 have been described above.

The transmitter 4420 may include the STL receiver 4421, BICM unit 4423,the framing/interleaving unit 4425 and the waveform generator 4427.

The transmitter 4430 may include the STL receiver 4431, BICM unit 4433,the framing/interleaving unit 4435 and the waveform generator 4437.

In this case, each of the STL receivers 4421 and 4431 receives the outertunnel data stream which is transmitted through the Studio toTransmitter Link (STL). In this case, the outer tunnel data stream maycorrespond to the channel bonding.

The STL receivers 4421 and 4431 may extract the outer packet from thereceived outer tunnel data stream, and extract the corresponding innerpacket. For this, the STL receivers 4421 and 4431 may extract the RTPpacket header, etc.

In particular, in the example of FIG. 44 , the STL receiver 4421receives the outer tunnel data stream (STL A) for the RF channel A, theSTL receiver 4431 receives the outer tunnel data stream (STL B) for theRF channel B, and each of the outer tunnel data streams (STL A, STL B)includes one inner tunneled packet stream group.

The structure and operation of the BICM units 4423 and 4433, theframing/interleaving units 4425 and 4435, and the waveform generators4427 and 4437 have been described above.

In the examples of FIG. 43 and FIG. 44 , the case where the plainchannel bonding is applied is explained. However, even when the SNRaveraging channel bonding is applied, the broadcast gateway apparatusmay generate the outer tunnel data stream as shown in FIG. 43 and FIG.44 and transmit it to the receiver(s) (the first mode).

When the SNR averaging channel bonding is applied, the broadcast gatewayapparatus may need to transmit the same outer tunnel data stream to thetransmitters for performing cell exchange module. To prevent this, theouter tunnel data stream may be generated by using the second mode to bedescribed below.

FIG. 45 is a block diagram showing one exemplarily embodiment of abroadcast signal transmission system when SNR averaging channel bondingfor colocated transmitters is applied.

Referring to FIG. 45 , only one outer tunnel data stream (STL) forchannel bonding is transmitted from the broadcast gateway apparatus 4510to the transmitter 4520.

In this case, the transmitter 4520 may be the colocated transmitter. Inthis case, the colocated transmitter may include multiple RFtransmission modules in a single transmitter to transmit channel-bondedRF transmission signals. That is, the colocated transmitter may includea plurality of physical layer chains.

For example, when the SNR averaging channel bonding is used, enabled byL1D_plp_channel_bonding_format = 01 in L1-Detail of the preamble, PLP(s)that would be processed through two RF channels of channel bonding mayuse two inner tunneled packet stream groups. In this case, the firstinner tunneled packet stream group corresponding to the first RF channelmay use the port 30000 - 30065, and the second inner tunneled packetstream group corresponding to the second RF channel may use the port30100 - 30165. In this case, the two inner tunneled packet stream groupsmay be transferred by one outer tunnel data stream.

For example, if L1D_plp_id = 1, one RF channel may use the port 30001for payload data, port 30064 for Preamble, and port 30065 for Timing andManagement Data. Then, the other RF channel may use the port 30101 forpayload data, port 30164 for Preamble, and port 30165 for Timing andManagement Data.

In the case of colocated transmitter in FIG. 45 , the transmitter 4520,which is required to perform the cell exchange after the BICM stage, mayreceive the one outer tunnel data stream that includes two innertunneled packet stream groups. Therefore, the transmitter 4520 may usethe port assignment of the inner tunneled packet stream group in orderto identify the packet corresponding to one among the plurality of RFchannels.

The broadcast gateway apparatus 4510 may include the input formattingunit 4511 and the stream partitioner 4513.

The transmitter 4520 may include the STL receiver 4521, the BICM units4523, the framing/interleaving units 4525, the waveform generators 4527and the cell exchanger 4529, and the operation of each block have beendescribed above.

FIG. 46 is a block diagram showing one exemplarily embodiment of abroadcast signal transmission system when SNR averaging channel bondingfor non-colocated transmitters is applied.

Referring to FIG. 46 , each of the transmitters 4620 and 4630 receivesthe same outer tunnel data stream from the broadcast gateway apparatus4610. In this case, the inner tunneled packet stream group correspondingto the RF channel A and the inner tunneled packet stream groupcorresponding to the RF channel B may be included in the outer tunneldata stream. Therefore, each transmitter may perform the cell exchangerby using the port assignment of the inner tunneled packet stream group,and then the only required cell data after the cell exchange may be usedfor the process through the selected RF channel of each transmitter.

In particular, for SNR averaging channel bonding transmitters 4620 and4630 at different locations (non-colocated), the broadcast gatewayapparatus 4610 may transmit two outer tunnel data streams which aredifferent from each other for the transmitter 4620 and the transmitter4630 unlike the case of FIG. 46 . In this case, each of the two outertunnel data streams which are different from each other may include twoinner tunneled packet stream groups for performing cell exchange.

For example, the outer tunnel data stream corresponding to the RFchannel A may include two inner tunneled packet stream groups forperforming cell exchange, and each inner tunneled packet stream groupmay be identified by the port 30001 and the port 30101 when L1D_plp_idis 1. In this case, the inner tunneled packet stream group correspondingto the port 30001 may include the stream to be transmitted through theRF channel A after performing cell exchange, and the inner tunneledpacket stream group corresponding to the port 30101 may be discardedafter performing cell exchange.

Similarly, the outer tunnel data stream corresponding to the RF channelB may include two inner tunneled packet stream groups for performingcell exchange, and each inner tunneled packet stream group may beidentified by the port 30001 and the port 30101 when L1D_plp_id is 1. Inthis case, the inner tunneled packet stream group corresponding to theport 30001 may include the stream to be transmitted through the RFchannel B after performing cell exchange, and the inner tunneled packetstream group corresponding to the port 30101 may be discarded afterperforming cell exchange.

As a result, the outer tunnel data stream including two inner tunneledpacket stream groups which is transmitted from the broadcast gatewayapparatus 4610 to the transmitter 4620 may correspond to STL A+B, andthe outer tunnel data stream including two inner tunneled packet streamgroups which is transmitted from the broadcast gateway apparatus 4610 tothe transmitter 4630 may correspond to STL B+A.

The broadcast gateway apparatus 4610 may include the input formattingunit 4611 and the stream partitioner 4613.

The transmitter 4620 may include the STL receiver 4621, the BICM units4623, the framing/interleaving units 4625, the waveform generators 4627and the cell exchanger 4629, and the operation of each block have beendescribed above.

In the examples of FIG. 45 and FIG. 46 , the case where the SNRaveraging channel bonding is applied is explained. However, even whenthe plain channel bonding is applied, the broadcast gateway apparatusmay generate the outer tunnel data stream as shown in FIG. 45 and FIG.46 and transmit it to the receiver(s) (the second mode).

In this case, when SNR averaging is applied as in the example of FIG. 45and FIG. 46 , the second mode (two or more inner tunneled packet streamgroups are included in one outer tunnel data stream) may be moreadvantageous than the first mode (outer tunnel data stream including oneinner tunneled packet stream group is assigned to each RF channel) interms of throughput. In particular, when non-colocated (two transmittersare positioned at different locations) channel bonding transmitters towhich SNR averaging is applied as shown in FIG. 46 are used, eachtransmitter may receive one outer tunnel data stream which includes twoinner tunneled packet stream groups. In this case, the two innertunneled packet stream groups may be divided into data (port 30001) tobe transmitted through the RF channel after performing cell exchange anddata (port 30101) that do not need to be transmitted to the RF channelafter the cell exchange. In the case of FIG. 46 , since each of twotransmitters need to receive two inner tunneled packet stream groups,STL throughput may be up to twice as compared to the case of thecollocated transmitter of FIG. 45 .

As shown in FIG. 43 ~ FIG. 46 , the broadcast gateway apparatus mayinclude the stream partitioner that allocates baseband packets ofchannel bonded PLP(s) to two RF channels when channel bonding is used.

For channel bonding, STLTP packet stream generation from the broadcastgateway apparatus may be enabled in one of two operation modes. In thiscase, the two operation modes may be selected by setting the channelnumber field (number_of_channels) of the outer packet header.

For example, when the channel number field (number_of_channels) is setto ‘0’ (the first mode), the broadcast gateway apparatus may generatetwo outer tunnel data streams, each of which may carry one innertunneled packet stream group corresponding to one RF channel as shown inFIG. 43 and FIG. 44 . In this case, each outer tunnel data stream mayinclude one inner tunneled packet stream group. In this case, the innertunneled packet stream group may comprise the Preamble, Timing andManagement, Baseband Packet, and Security Data Streams required for oneRF channel.

For example, when the channel number field (number_of channels) is setto ‘1’ (the second mode), the broadcast gateway apparatus may generateone outer tunnel data stream that carries two inner tunneled packetstream groups, each of which corresponds to each RF channel, as shown inFIG. 45 and FIG. 46 . In this case, the one outer tunnel data stream mayinclude two inner tunneled packet stream groups.

When the channel number field (number_of_channels) is set to ‘1’ (thesecond mode), the two inner tunneled packet stream groups may beidentified by different port assignments. That is, one inner tunneledpacket stream group may appear on ports 30000 - 30066, and the otherinner tunneled packet stream group may appear on ports 30100 - 30166.

The first mode or the second mode described above may be used for bothplain channel bonding and SNR averaging channel bonding.

As explained above, the outer tunnel data stream may be generated indifferent ways according to the operation modes for channel bonding.

In this case, the operation modes may include a first mode in which oneouter tunnel data stream is generated for each of the two or more RFchannels; and a second mode in which one outer tunnel data stream forthe two or more RF channels is generated.

In this case, the one outer tunnel data stream for the first mode mayinclude one inner tunneled packet stream group for one among the two ormore RF channels. In this case, the one outer tunnel data stream of thesecond mode may include two or more inner tunneled packet stream groupseach of which is for each RF channel.

In this case, the outer tunnel data stream may be transmitted to atransmitter through a Studio-to-Transmitter Link (STL), and maycorrespond to an outer layer of a tunneling system and the innertunneled packet stream group may correspond to an inner layer of thetunneling system.

In this case, the two or more inner tunneled packet stream groups of thesecond mode may use port groups different from each other.

In this case, the two or more RF channels may be two RF channels, and afirst port group corresponding to ports 30000 - 30066 may be used forthe inner tunneled packet stream group corresponding to a first channelamong the two RF channels and a second port group corresponding to ports30100 - 30166 may be used for the inner tunneled packet stream groupcorresponding to a second channel among the two RF channels.

In this case, the outer tunnel data stream may include a RTP headerwhich includes a channel number field (number_of channels) thatindicates the number of channels corresponding to the outer tunnel datastream.

In this case, the channel number field may be 2-bit field, and may beset to ‘0’ for the first mode and may be set to ‘1’ for the second mode.

The following Table 3 shows an example of the header of an outer packet(a broadcast transmission packet, a tunneling packet).

TABLE 3 Syntax No. of Bits Format RTP_Fixed_Header() { version (V) 2‘10’ padding (P) 1 bslbf extension (X) 1 ‘0’ CSRC_count (CC) 4 ‘0000’marker (M) 1 bslbf payload_type (PT) 7 ‘1100001’ sequence_number 16uimsbf timestamp 32 protocol_version 2 uimsbf redundancy 2 uimsbfnumber_of_channels 2 uimsbf reserved 10 for (i=0; i<10; i++) ‘0’packet_offset 16 uimsbf }

In Table 3, ‘uimsbf’ means unsigned integer, most significant bit first,and ‘bslbf’ means bit stream, leftmost bit first.

In the example of Table 3, the header of an outer packet may correspondto RTP_Fixed_Header(), the sequence number field may correspond tosequence_number, the redundancy field may correspond to redundancy, andthe channel number field may correspond to number_of_channels.

Here, the header of an outer packet in Table 3 may be a kind of RTPheader.

Here, sequence_number may be used when a transmitter receiving outerpackets identifies redundant packets, and may be increased by one foreach packet of an RTP stream.

Here, redundancy may indicate the number of redundant streams of outerpackets transmitted to the Studio-to-Transmitter Link.

Here, redundancy is a two-bit field, and may be set to any one of ‘0’,‘1’, ‘2’ and ‘3’. For example, when redundancy is set to ‘0’, this mayindicate that there are no redundant copies of the outer packet. Whenredundancy is set to ‘3’, this may indicate that the number of redundantcopies of the outer packet is 3 (that is, a total of four identicalpackets are transmitted).

In this case, number_of_channels may be 2-bit field and set to a valuecorresponding to the number of broadcast channels which are transmittedby the corresponding outer tunnel data stream. For example,number_of_channels may indicate the number of broadcast channels minusone transported by the outer tunnel data stream.

When this field is set to ‘0’, one outer tunneling stream may includeone inner tunneled packet stream group. In this case, the inner tunneledpacket stream group may use the port range 30000 - 30066. In this case,the inner tunneled packet stream group may comprise the preamble, timingand management, baseband packet, and security data streams required fortransmission of one RF channel.

When this field is set to ‘1’, one outer tunnel data stream may includetwo inner tunneled packet stream groups. When this field is set to ‘1’,the port range of one inner tunneled packet stream group (correspondingto one RF channel) may be 30000 -30066, and the port range of the otherinner tunneled packet stream group (corresponding to the other RFchannel) may be 30100 - 30166.

FIG. 47 is an operation flowchart showing an example of abroadcast-gateway-signaling method according to an embodiment of thepresent invention.

Referring to FIG. 47 , the broadcast-gateway-signaling method accordingto an embodiment of the present invention generates baseband packetscorresponding to channel bonding at step S4710.

Furthermore, the broadcast-gateway-signaling method according to anembodiment of the present invention allocates the baseband packets totwo or more RF channels of the channel bonding for generating an outertunnel data stream at step S4720. In this case, the outer tunnel datastream is generated in different ways according to a plurality ofoperation modes for the channel bonding.

In this case, the plurality of operation modes may include a first modein which one outer tunnel data stream is generated for each of the twoor more RF channels; and a second mode in which one outer tunnel datastream for the two or more RF channels is generated.

In this case, the one outer tunnel data stream for the first mode mayinclude one inner tunneled packet stream group for one among the two ormore RF channels.

In this case, the one outer tunnel data stream of the second mode mayinclude two or more inner tunneled packet stream groups each of which isfor each of the two or more RF channels.

In this case, the two or more inner tunneled packet stream groups of thesecond mode may use different port groups.

In this case, the outer tunnel data steam may include a RTP header whichinclude a channel number field (number_of channels) that indicates thenumber of channels corresponding to the outer tunnel data stream.

Furthermore, the broadcast-gateway-signaling method according to anembodiment of the present invention transmits the outer tunnel datastream to a transmitter through Studio to Transmitter Link (STL) at stepS4730.

FIG. 48 is an operation flowchart showing an example of a broadcastsignal transmission method according to an embodiment of the presentinvention.

Referring to FIG. 48 , the broadcast signal transmission methodaccording to an embodiment of the present invention receives an outertunnel data stream which is transmitted through a Studio-to-TransmitterLink (STL) and corresponds to channel bonding at step S4810.

In this case, the outer tunnel data stream may be generated in differentways according to a plurality of operation modes for the channelbonding.

In this case, the plurality of operation modes may include a first modein which one outer tunnel data stream is generated for each of the twoor more RF channels; and a second mode in which one outer tunnel datastream for the two or more RF channels is generated.

Furthermore, the broadcast signal transmission method according to anembodiment of the present invention performs error correction encoding,interleaving and modulation corresponding to one among two or more RFchannels corresponding to the channel bonding at step S4820.

Furthermore, the broadcast signal transmission method according to anembodiment of the present invention generates a RF transmission signalcorresponding to the one among two or more RF channels at step S4830.

FIG. 49 is a block diagram showing a computer system according to anembodiment of the present invention.

Referring to FIG. 49 , the broadcast gateway apparatus and/or thebroadcast signal transmission apparatus according to an embodiment ofthe present invention may be implemented in a computer system 900including a computer-readable recording medium. As illustrated in FIG.49 , the computer system 900 may include one or more processors 910,memory 930, a user-interface input device 940, a user-interface outputdevice 950, and storage 960, which communicate with each other via a bus920. Also, the computer system 900 may further include a networkinterface 970 connected to a network 980. The processor 910 may be acentral processing unit or a semiconductor device for executingprocessing instructions stored in the memory 930 or the storage 960. Thememory 930 and the storage 960 may be any of various types of volatileor nonvolatile storage media. For example, the memory may include ROM931 or RAM 932.

According to the present invention, each broadcast transmission signalcorresponding to each RF channel may be efficiently generated when thechannel bonding is performed using two or more RF channels.

Also, the present invention may provide a channel bonding serviceefficiently by appropriately sharing roles of a broadcast gateway and atransmitter.

Also, the present invention may optimize the throughput of a broadcastgateway apparatus even when SNR averaging channel bonding is applied.

Also, the present invention may optimize a broadcast-gateway-signalingfield for the channel bonding service.

As described above, the broadcast-gateway-signaling method and apparatusaccording to the present invention are not limitedly applied to theconfigurations and operations of the above-described embodiments, butall or some of the embodiments may be selectively combined andconfigured, so that the embodiments may be modified in various ways.

What is claimed is:
 1. A broadcast gateway apparatus, comprising: aninput formatting unit configured to generate baseband packetscorresponding to channel bonding; and a stream partitioner configured toallocate the baseband packets to two or more RF channels of the channelbonding for generating an outer tunnel data stream, the outer tunneldata stream generated in different ways according to operation modes forthe channel bonding, wherein the channel bonding is performed by plainchannel bonding or SNR averaging channel bonding, and wherein the outertunnel data stream includes a RTP header which includes a channel numberfield (number_of_channels) that indicates the number of channelscorresponding to the outer tunnel data stream.
 2. The broadcast gatewayapparatus of claim 1, wherein the operation modes include: a first modein which one outer tunnel data stream is generated for each of the twoor more RF channels; and a second mode in which one outer tunnel datastream is generated for the two or more RF channels.
 3. The broadcastgateway apparatus of claim 2, wherein the one outer tunnel data streamof the first mode includes one inner tunneled packet stream group forone among the two or more RF channels, and the one outer tunnel datastream of the second mode includes two or more inner tunneled packetstream groups, the two or more inner tunneled packet stream groups beingfor the two or more RF channels, respectively.
 4. The broadcast gatewayapparatus of claim 3, wherein the outer tunnel data stream istransmitted to a transmitter through a Studio-to-Transmitter Link (STL)and corresponds to an outer layer of a tunneling system, and the innertunneled packet stream group corresponds to an inner layer of thetunneling system.
 5. The broadcast gateway apparatus of claim 3, whereinthe two or more inner tunneled packet stream groups of the second modeuse different port groups.
 6. The broadcast gateway apparatus of claim5, wherein the second mode uses two outer tunnel data streams for twonon-colocated transmitters corresponding to SNR averaging channelbonding, and each of the two outer tunnel data streams includes twoinner tunneled packet stream groups which use different port groups. 7.The broadcast gateway apparatus of claim 5, wherein the two or more RFchannels are two RF channels, a first port group corresponding to ports30000 - 30066 is used for the inner tunneled packet stream groupcorresponding to a first channel among the two RF channels, and a secondport group corresponding to ports 30100 - 30166 is used for the innertunneled packet stream group corresponding to a second channel among thetwo RF channels.
 8. The broadcast gateway apparatus of claim 1, whereinthe channel number field is 2-bit field, is set to ‘0’ for the firstmode, and is set to ‘1’ for the second mode.
 9. An apparatus oftransmitting a broadcast signal, comprising: a STL receiver configuredto receive an outer tunnel data stream transmitted through aStudio-to-Transmitter Link (STL), the outer tunnel data streamcorresponding to channel bonding; a BICM unit configured to performerror correction encoding, interleaving and modulation corresponding toone among two or more RF channels corresponding to the channel bonding;and a waveform generator configured to generate a RF transmission signalcorresponding to the one among two or more RF channels, wherein thechannel bonding is performed by plain channel bonding or SNR averagingchannel bonding, and wherein the outer tunnel data stream includes a RTPheader which includes a channel number field (number_of_channels) thatindicates the number of channels corresponding to the outer tunnel datastream.
 10. The apparatus of claim 9, wherein the outer tunnel datastream is generated in different ways according to operation modes forthe channel bonding.
 11. The apparatus of claim 10, wherein theoperation modes include: a first mode in which one outer tunnel datastream is generated for each of the two or more RF channels; and asecond mode in which one outer tunnel data stream is generated for thetwo or more RF channels.
 12. The apparatus of claim 11, wherein the oneouter tunnel data stream of the first mode includes one inner tunneledpacket stream group for one among the two or more RF channels, and theone outer tunnel data stream of the second mode includes two or moreinner tunneled packet stream groups, the two or more inner tunneledpacket stream groups being for the two or more RF channels,respectively.
 13. The apparatus of claim 12, wherein the two or moreinner tunneled packet stream groups of the second mode use differentport groups.
 14. A broadcast-gateway-signaling method, comprising:generating baseband packets corresponding to channel bonding; andallocating the baseband packets to two or more RF channels of thechannel bonding for generating an outer tunnel data stream, the outertunnel data stream generated in different ways according to operationmodes for the channel bonding, wherein the channel bonding is performedby plain channel bonding or SNR averaging channel bonding, and whereinthe outer tunnel data stream includes a RTP header which includes achannel number field (number_of_channels) that indicates the number ofchannels corresponding to the outer tunnel data stream.
 15. Thebroadcast-gateway-signaling method of claim 14, wherein the operationmodes include: a first mode in which one outer tunnel data stream isgenerated for each of the two or more RF channels; and a second mode inwhich one outer tunnel data stream is generated for the two or more RFchannels.
 16. The broadcast-gateway-signaling method of claim 15,wherein the one outer tunnel data stream of the first mode includes oneinner tunneled packet stream group for one among the two or more RFchannels, and the one outer tunnel data stream of the second modeincludes two or more inner tunneled packet stream groups, the two ormore inner tunneled packet stream groups being for the two or more RFchannels, respectively.
 17. The broadcast-gateway-signaling method ofclaim 16, wherein the two or more inner tunneled packet stream groups ofthe second mode use different port groups.